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http://rosettacode.org/wiki/Horizontal_sundial_calculations
Horizontal sundial calculations
Task Create a program that calculates the hour, sun hour angle, dial hour line angle from 6am to 6pm for an operator entered location. For example, the user is prompted for a location and inputs the latitude and longitude 4°57′S 150°30′W (4.95°S 150.5°W of Jules Verne's Lincoln Island, aka Ernest Legouve Reef), wit...
#.D0.9C.D0.9A-61.2F52
МК-61/52
МГ П2 -> МГ П1 -> МГ sin П0 6 /-/ П3 ИП3 1 5 * ИП1 ИП2 - - П4 tg ИП0 * arctg ИП4 ИП3 С/П ИП3 1 + П3 7 - x=0 12 Сx С/П
http://rosettacode.org/wiki/Horizontal_sundial_calculations
Horizontal sundial calculations
Task Create a program that calculates the hour, sun hour angle, dial hour line angle from 6am to 6pm for an operator entered location. For example, the user is prompted for a location and inputs the latitude and longitude 4°57′S 150°30′W (4.95°S 150.5°W of Jules Verne's Lincoln Island, aka Ernest Legouve Reef), wit...
#Modula-2
Modula-2
  MODULE SunDial;   FROM STextIO IMPORT WriteString, WriteLn, SkipLine; FROM SRealIO IMPORT ReadReal, WriteFixed, WriteFloat; FROM SWholeIO IMPORT WriteInt; FROM RealMath IMPORT sin, pi, arctan, tan;   VAR Lat, Slat, Lng, Ref: REAL; Hour: INTEGER; HourAngle, HourLineAngle: REAL; BEGIN WriteString("Enter...
http://rosettacode.org/wiki/Huffman_coding
Huffman coding
Huffman encoding is a way to assign binary codes to symbols that reduces the overall number of bits used to encode a typical string of those symbols. For example, if you use letters as symbols and have details of the frequency of occurrence of those letters in typical strings, then you could just encode each letter wi...
#Picat
Picat
go => huffman("this is an example for huffman encoding").   huffman(LA) :- LS=sort(LA), packList(LS,PL), PLS=sort(PL).remove_dups(), build_tree(PLS, A), coding(A, [], C), SC=sort(C).remove_dups(), println("Symbol\tWeight\tCode"), foreach(SS in SC) print_code(SS) end.   build_tree([[V1|R1], [V2...
http://rosettacode.org/wiki/Identity_matrix
Identity matrix
Task Build an   identity matrix   of a size known at run-time. An identity matrix is a square matrix of size n × n, where the diagonal elements are all 1s (ones), and all the other elements are all 0s (zeroes). I n = [ 1 0 0 ⋯ 0 0 1 0 ⋯ 0 0 0 1 ⋯ 0 ⋮ ⋮ ⋮ ⋱ ...
#Scala
Scala
def identityMatrix(n:Int)=Array.tabulate(n,n)((x,y) => if(x==y) 1 else 0) def printMatrix[T](m:Array[Array[T]])=m map (_.mkString("[", ", ", "]")) mkString "\n"   printMatrix(identityMatrix(5))
http://rosettacode.org/wiki/Integer_comparison
Integer comparison
Basic Data Operation This is a basic data operation. It represents a fundamental action on a basic data type. You may see other such operations in the Basic Data Operations category, or: Integer Operations Arithmetic | Comparison Boolean Operations Bitwise | Logical String Operations Concatenation | Interpolation |...
#SAS
SAS
/* Showing operators and their fortran-like equivalents. Note that ~= and ^= both mean "different" */ data _null_; input a b; put a= b=; if a = b then put "a = b"; if a ^= b then put "a ^= b"; if a ~= b then put "a ~= b"; if a < b then put "a < b"; if a > b then put "a > b"; if a <= b then put "a <= b"; if a >= b then ...
http://rosettacode.org/wiki/HTTP
HTTP
Task Access and print a URL's content (the located resource) to the console. There is a separate task for HTTPS Requests.
#Groovy
Groovy
  new URL("http://www.rosettacode.org").eachLine { println it }  
http://rosettacode.org/wiki/Hofstadter-Conway_$10,000_sequence
Hofstadter-Conway $10,000 sequence
The definition of the sequence is colloquially described as:   Starting with the list [1,1],   Take the last number in the list so far: 1, I'll call it x.   Count forward x places from the beginning of the list to find the first number to add (1)   Count backward x places from the end of the list to find the secon...
#JavaScript
JavaScript
var hofst_10k = function(n) { var memo = [1, 1];   var a = function(n) { var result = memo[n-1]; if (typeof result !== 'number') { result = a(a(n-1))+a(n-a(n-1)); memo[n-1] = result; } return result; } return a; }();   var maxima_between_twos = function(exp) { var current_max = 0; for(var i = Math...
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#E
E
stderr.println("Goodbye, World!")
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#Elixir
Elixir
IO.puts :stderr, "Goodbye, World!"
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#Emacs_Lisp
Emacs Lisp
(message "Goodbye, World!")
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#Erlang
Erlang
io:put_chars(standard_error, "Goodbye, World!\n").
http://rosettacode.org/wiki/Hofstadter_Q_sequence
Hofstadter Q sequence
Hofstadter Q sequence Q ( 1 ) = Q ( 2 ) = 1 , Q ( n ) = Q ( n − Q ( n − 1 ) ) + Q ( n − Q ( n − 2 ) ) , n > 2. {\displaystyle {\begin{aligned}Q(1)&=Q(2)=1,\\Q(n)&=Q{\big (}n-Q(n-1){\big )}+Q{\big (}n-Q(n-2){\big )},\quad n>2.\end{aligned}}} It is defined like the Fibonacc...
#Elixir
Elixir
defmodule Hofstadter do defp flip(v2, v1) when v1 > v2, do: 1 defp flip(_v2, _v1), do: 0   defp list_terms(max, n, acc), do: Enum.map_join(n..max, ", ", &acc[&1])   defp hofstadter(n, n, acc, flips) do IO.puts "The first ten terms are: #{list_terms(10, 1, acc)}" IO.puts "The 1000'th term is #{acc[1000]}...
http://rosettacode.org/wiki/Hickerson_series_of_almost_integers
Hickerson series of almost integers
The following function,   due to D. Hickerson,   is said to generate "Almost integers" by the "Almost Integer" page of Wolfram MathWorld,   (December 31 2013).   (See formula numbered   51.) The function is:           h ( n ) = n ! 2 ( ln ⁡ 2 ) n + 1 {\displaystyle h(n)={\operatorname {n} ! \ove...
#PL.2FI
PL/I
Hickerson: procedure options (main); /* 12 January 2014 */ declare s float (18), (i, n) fixed binary; declare is fixed decimal (30); declare f fixed decimal (4,3);   do n = 1 to 16; /* 17 exceeds hardware precision */ s = 0.5Q0 / 0.693147180559945309417232121458; do i = 1 to n; s = (s *...
http://rosettacode.org/wiki/Hello_world/Text
Hello world/Text
Hello world/Text is part of Short Circuit's Console Program Basics selection. Task Display the string Hello world! on a text console. Related tasks   Hello world/Graphical   Hello world/Line Printer   Hello world/Newbie   Hello world/Newline omission   Hello world/Standard error   Hello world/Web server
#8080_Assembly
8080 Assembly
; This is Hello World, written in 8080 assembly to run under CP/M ; As you can see, it is similar to the 8086, and CP/M is very ; similar to DOS in the way it is called. org 100h ; CP/M .COM entry point is 100h - like DOS mvi c,9 ; C holds the syscall, 9 = print string - like DOS lxi d,msg ; DE holds a pointer to...
http://rosettacode.org/wiki/Heronian_triangles
Heronian triangles
Hero's formula for the area of a triangle given the length of its three sides   a,   b,   and   c   is given by: A = s ( s − a ) ( s − b ) ( s − c ) , {\displaystyle A={\sqrt {s(s-a)(s-b)(s-c)}},} where   s   is half the perimeter of the triangle; that is, s = a + b + c 2 . {\displaystyle s...
#Elixir
Elixir
defmodule Heronian do def triangle?(a,b,c) when a+b <= c, do: false def triangle?(a,b,c) do area = area(a,b,c) area == round(area) and primitive?(a,b,c) end   def area(a,b,c) do s = (a + b + c) / 2  :math.sqrt(s * (s-a) * (s-b) * (s-c)) end   defp primitive?(a,b,c), do: gcd(gcd(a,b),c) == 1  ...
http://rosettacode.org/wiki/Heronian_triangles
Heronian triangles
Hero's formula for the area of a triangle given the length of its three sides   a,   b,   and   c   is given by: A = s ( s − a ) ( s − b ) ( s − c ) , {\displaystyle A={\sqrt {s(s-a)(s-b)(s-c)}},} where   s   is half the perimeter of the triangle; that is, s = a + b + c 2 . {\displaystyle s...
#ERRE
ERRE
  PROGRAM HERON   DIM LISTA%[600,4]   PROCEDURE GCD(J%,K%->MCD%) WHILE J%<>K% DO IF J%>K% THEN J%=J%-K% ELSE K%=K%-J% END IF END WHILE MCD%=J% END PROCEDURE   BEGIN PRINT(CHR$(12);) !CLS FOR C%=1 TO 200 DO FOR B%=1 TO C% DO FOR A%=1 TO B% DO ...
http://rosettacode.org/wiki/Higher-order_functions
Higher-order functions
Task Pass a function     as an argument     to another function. Related task   First-class functions
#BQN
BQN
Uniq ← ⍷   •Show uniq {𝕎𝕩} 5‿6‿7‿5
http://rosettacode.org/wiki/Hello_world/Web_server
Hello world/Web server
The browser is the new GUI ! Task Serve our standard text   Goodbye, World!   to   http://localhost:8080/   so that it can be viewed with a web browser. The provided solution must start or implement a server that accepts multiple client connections and serves text as requested. Note that starting a web browser or...
#Genie
Genie
/** * Based on https://wiki.gnome.org/Projects/Genie/GIONetworkingSample * Based on an example of Jezra Lickter http://hoof.jezra.net/snip/nV * * valac --pkg gio-2.0 --pkg gee-0.8 webserver.gs * ./webserver */ [indent=8] uses GLib Gee   init var ws = new WebServer() ws.run()   str...
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#Lambdatalk
Lambdatalk
  1) defining a variable: {def myVar 123}   2) defining some text: Here is some multi-line string. And here is the value of "myVar": '{myVar} That's all.   3) displays :   Here is some multi-line string. And here is the value of "myVar": 123 That's all.  
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#langur
langur
val .s = q:block END We put our text here. Here we are, Doc. END
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#Lingo
Lingo
str = "This is the first line.\ This is the second line.\ This "&QUOTE&"line"&QUOTE&" contains quotes."   put str
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#Lua
Lua
  print([[ This is a long paragraph of text it is the simplest while using it with lua, however it will have the same line breaks and spacing as you set in this block. ]])   print([=[by using equals signs, ]] may be embedded.]=])   local msg = [[this is a message that spans multiple lines and will have the next li...
http://rosettacode.org/wiki/History_variables
History variables
Storing the history of objects in a program is a common task. Maintaining the history of an object in a program has traditionally required programmers either to write specific code for handling the historical data, or to use a library which supports history logging. History variables are variables in a programming la...
#Racket
Racket
  #lang racket   (require rackunit)   (struct hvar (current history) #:mutable)   (define (make-hvar v) (hvar v empty))   (define (hvar-set! hv new) (match-define (hvar cur hist) hv) (set-hvar-history! hv (cons cur hist)) (set-hvar-current! hv new))   (define (hvar-undo! hv) (match-define (hvar cur (cons old hi...
http://rosettacode.org/wiki/History_variables
History variables
Storing the history of objects in a program is a common task. Maintaining the history of an object in a program has traditionally required programmers either to write specific code for handling the historical data, or to use a library which supports history logging. History variables are variables in a programming la...
#Raku
Raku
class HistoryVar { has @.history; has $!var handles <Str gist FETCH Numeric>; method STORE($val) is rw { push @.history, [now, $!var]; $!var = $val; } }   my \foo = HistoryVar.new;   foo = 1; foo = 2; foo += 3; foo = 42;   .say for foo.history; say "Current value: {foo}";
http://rosettacode.org/wiki/Hofstadter_Figure-Figure_sequences
Hofstadter Figure-Figure sequences
These two sequences of positive integers are defined as: R ( 1 ) = 1   ;   S ( 1 ) = 2 R ( n ) = R ( n − 1 ) + S ( n − 1 ) , n > 1. {\displaystyle {\begin{aligned}R(1)&=1\ ;\ S(1)=2\\R(n)&=R(n-1)+S(n-1),\quad n>1.\end{aligned}}} The sequence S ( n ) {\displaystyle S(n)} is further...
#Mathematica_.2F_Wolfram_Language
Mathematica / Wolfram Language
The instructions call for two functions. Because S[n] is generated while computing R[n], one would normally avoid redundancy by combining R and S into a single function that returns both sequences.
http://rosettacode.org/wiki/Hofstadter_Figure-Figure_sequences
Hofstadter Figure-Figure sequences
These two sequences of positive integers are defined as: R ( 1 ) = 1   ;   S ( 1 ) = 2 R ( n ) = R ( n − 1 ) + S ( n − 1 ) , n > 1. {\displaystyle {\begin{aligned}R(1)&=1\ ;\ S(1)=2\\R(n)&=R(n-1)+S(n-1),\quad n>1.\end{aligned}}} The sequence S ( n ) {\displaystyle S(n)} is further...
#MATLAB_.2F_Octave
MATLAB / Octave
function [R,S] = ffr_ffs(N) t = [1,0]; T = 1; n = 1; %while T<=1000, while n<=N, R = find(t,n); S = find(~t,n); T = R(n)+S(n);   % pre-allocate memory, this improves performance if T > length(t), t = [t,zeros(size(t))]; end;   t(T) = 1; n = n ...
http://rosettacode.org/wiki/Horner%27s_rule_for_polynomial_evaluation
Horner's rule for polynomial evaluation
A fast scheme for evaluating a polynomial such as: − 19 + 7 x − 4 x 2 + 6 x 3 {\displaystyle -19+7x-4x^{2}+6x^{3}\,} when x = 3 {\displaystyle x=3\;} . is to arrange the computation as follows: ( ( ( ( 0 ) x + 6 ) x + ( − 4 ) ) x + 7 ) x + ( − 19 ) {\displaystyle ((((0)x+6)x+(-4))x...
#MATLAB
MATLAB
function accumulator = hornersRule(x,coefficients)   accumulator = 0;   for i = (numel(coefficients):-1:1) accumulator = (accumulator * x) + coefficients(i); end   end
http://rosettacode.org/wiki/Horner%27s_rule_for_polynomial_evaluation
Horner's rule for polynomial evaluation
A fast scheme for evaluating a polynomial such as: − 19 + 7 x − 4 x 2 + 6 x 3 {\displaystyle -19+7x-4x^{2}+6x^{3}\,} when x = 3 {\displaystyle x=3\;} . is to arrange the computation as follows: ( ( ( ( 0 ) x + 6 ) x + ( − 4 ) ) x + 7 ) x + ( − 19 ) {\displaystyle ((((0)x+6)x+(-4))x...
#Maxima
Maxima
/* Function horner already exists in Maxima, though it operates on expressions, not lists of coefficients */ horner(5*x^3+2*x+1); x*(5*x^2+2)+1   /* Here is an implementation */ horner2(p, x) := block([n, y, i], n: length(p), y: p[n], for i: n - 1 step -1 thru 1 do y: y*x + p[i], y )$   horner2([-19, 7, -4,...
http://rosettacode.org/wiki/Hilbert_curve
Hilbert curve
Task Produce a graphical or ASCII-art representation of a Hilbert curve of at least order 3.
#Mathematica.2FWolfram_Language
Mathematica/Wolfram Language
Graphics@HilbertCurve[4]
http://rosettacode.org/wiki/Hilbert_curve
Hilbert curve
Task Produce a graphical or ASCII-art representation of a Hilbert curve of at least order 3.
#Nim
Nim
const Level = 4 Side = (1 shl Level) * 2 - 2   type Direction = enum E, N, W, S   const   # Strings to use according to direction. Drawings1: array[Direction, string] = ["──", " │", "──", " │"]   # Strings to use according to old and current direction. Drawings2: array[Direction, array[Direction, string]] =...
http://rosettacode.org/wiki/Honeycombs
Honeycombs
The task is to produce a matrix of 20 hexagon shaped widgets in a honeycomb arrangement. The matrix should be arranged in such a manner that there are five columns of four hexagons. The hexagons in columns one, three and five are aligned horizontally, whereas the hexagons in columns two and four occupy a lower position...
#Wren
Wren
import "graphics" for Canvas, Color import "dome" for Window, Process import "math" for Math import "font" for Font import "input" for Mouse, Keyboard import "random" for Random import "./polygon" for Polygon   var Rand = Random.new()   class Hexagon is Polygon { static baseColor { Color.yellow } static selecte...
http://rosettacode.org/wiki/Holidays_related_to_Easter
Holidays related to Easter
Task Calculate the dates of:   Easter   Ascension Thursday   Pentecost   Trinity Sunday   Corpus Christi feast (for Catholic)   All Saints' Sunday (for Orthodox) As an example, calculate for the first year of each century from;   years     400   to   2100 CE   and for   years   2010   to   2020 CE. Note ...
#Julia
Julia
# v0.6   using Dates   function easter(year::Int)::Date a = rem(year, 19) b, c = divrem(year, 100) d = rem(19a + b - div(b, 4) - div(b - div(b + 8, 25) + 1, 3) + 15, 30) e = rem(32 + 2 * rem(b, 4) + 2 * div(c, 4) - d - rem(c, 4), 7) f = d + e - 7 * div(a + 11d + 22e, 451) + 114 month, day = divr...
http://rosettacode.org/wiki/Horizontal_sundial_calculations
Horizontal sundial calculations
Task Create a program that calculates the hour, sun hour angle, dial hour line angle from 6am to 6pm for an operator entered location. For example, the user is prompted for a location and inputs the latitude and longitude 4°57′S 150°30′W (4.95°S 150.5°W of Jules Verne's Lincoln Island, aka Ernest Legouve Reef), wit...
#newLISP
newLISP
(define pi 3.141592654) (define (radians degrees) (mul degrees (div pi 180))) (define (degrees radians) (mul radians (div 180 pi)))   (print "Enter latitude => ") (set 'lat (float (read-line)))   (print "Enter longitude => ") (set 'lng (float (read-line)))   (print "Enter legal meridian => ") (set 'rf (float...
http://rosettacode.org/wiki/Huffman_coding
Huffman coding
Huffman encoding is a way to assign binary codes to symbols that reduces the overall number of bits used to encode a typical string of those symbols. For example, if you use letters as symbols and have details of the frequency of occurrence of those letters in typical strings, then you could just encode each letter wi...
#PicoLisp
PicoLisp
(de prio (Idx) (while (cadr Idx) (setq Idx @)) (car Idx) )   (let (A NIL P NIL L NIL) (for C (chop "this is an example for huffman encoding") (accu 'A C 1) ) # Count characters (for X A # Build index tree as priority queue (idx 'P (cons (cdr X) (car ...
http://rosettacode.org/wiki/Identity_matrix
Identity matrix
Task Build an   identity matrix   of a size known at run-time. An identity matrix is a square matrix of size n × n, where the diagonal elements are all 1s (ones), and all the other elements are all 0s (zeroes). I n = [ 1 0 0 ⋯ 0 0 1 0 ⋯ 0 0 0 1 ⋯ 0 ⋮ ⋮ ⋮ ⋱ ...
#Scheme
Scheme
  (define (identity n) (letrec ((uvec (lambda (m i acc) (if (= i n) acc (uvec m (+ i 1) (cons (if (= i m) 1 0) acc))))) (idgen (lambda (i acc) (if (= i n) acc (idgen (+ i 1) (cons (uvec i 0 '()) acc)))))) (idgen 0 '())))  
http://rosettacode.org/wiki/Integer_comparison
Integer comparison
Basic Data Operation This is a basic data operation. It represents a fundamental action on a basic data type. You may see other such operations in the Basic Data Operations category, or: Integer Operations Arithmetic | Comparison Boolean Operations Bitwise | Logical String Operations Concatenation | Interpolation |...
#Scala
Scala
object IntCompare { def main(args: Array[String]): Unit = { val a=Console.readInt val b=Console.readInt if (a < b) printf("%d is less than %d\n", a, b) if (a == b) printf("%d is equal to %d\n", a, b) if (a > b) printf("%d is greater than %d\n", a, b) } }
http://rosettacode.org/wiki/Integer_comparison
Integer comparison
Basic Data Operation This is a basic data operation. It represents a fundamental action on a basic data type. You may see other such operations in the Basic Data Operations category, or: Integer Operations Arithmetic | Comparison Boolean Operations Bitwise | Logical String Operations Concatenation | Interpolation |...
#Scheme
Scheme
(define (my-compare a b) (cond ((< a b) "A is less than B") ((> a b) "A is greater than B") ((= a b) "A equals B")))   (my-compare (read) (read))
http://rosettacode.org/wiki/HTTP
HTTP
Task Access and print a URL's content (the located resource) to the console. There is a separate task for HTTPS Requests.
#GUISS
GUISS
Start,Programs,Applications,Mozilla Firefox,Inputbox:address bar>www.rosettacode.org,Button:Go, Click:Area:browser window,Type:[Control A],[Control C],Start,Programs,Accessories,Notepad, Menu:Edit,Paste
http://rosettacode.org/wiki/Hofstadter-Conway_$10,000_sequence
Hofstadter-Conway $10,000 sequence
The definition of the sequence is colloquially described as:   Starting with the list [1,1],   Take the last number in the list so far: 1, I'll call it x.   Count forward x places from the beginning of the list to find the first number to add (1)   Count backward x places from the end of the list to find the secon...
#jq
jq
def hcSequence($limit): reduce range(3; $limit) as $n ([0,1,1]; .[$n-1] as $p | .[$n] = .[$p] + .[$n-$p]);   def task($limit): hcSequence($limit) as $a | " Range Maximum", "---------------- --------", (foreach range(2; $limit) as $n ( {max: $a[1], pow2: 1, p:1 }; ($a[$n] / $n...
http://rosettacode.org/wiki/Hofstadter-Conway_$10,000_sequence
Hofstadter-Conway $10,000 sequence
The definition of the sequence is colloquially described as:   Starting with the list [1,1],   Take the last number in the list so far: 1, I'll call it x.   Count forward x places from the beginning of the list to find the first number to add (1)   Count backward x places from the end of the list to find the secon...
#Julia
Julia
# v0.6   # Task 1 function hofstadterconway(n::Integer)::Vector{Int} rst = fill(1, n) for i in 3:n rst[i] = rst[rst[i - 1]] + rst[i - rst[i - 1]] end return rst end   function hcfraction(n::Integer)::Vector{Float64} rst = Array{Float64}(n) for (i, a) in enumerate(hofstadterconway(n)) ...
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#Euphoria
Euphoria
puts(2,"Goodbye, world!\n") -- 2 means output to 'standard error'
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#F.23
F#
eprintfn "%s" "Goodbye, World!"
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#Factor
Factor
error-stream get [ "Goodbye, World! bbl, crashing" print flush ] with-output-stream*
http://rosettacode.org/wiki/Hofstadter_Q_sequence
Hofstadter Q sequence
Hofstadter Q sequence Q ( 1 ) = Q ( 2 ) = 1 , Q ( n ) = Q ( n − Q ( n − 1 ) ) + Q ( n − Q ( n − 2 ) ) , n > 2. {\displaystyle {\begin{aligned}Q(1)&=Q(2)=1,\\Q(n)&=Q{\big (}n-Q(n-1){\big )}+Q{\big (}n-Q(n-2){\big )},\quad n>2.\end{aligned}}} It is defined like the Fibonacc...
#Erlang
Erlang
%% @author Jan Willem Luiten <jwl@secondmove.com> %% Hofstadter Q Sequence for Rosetta Code   -module(hofstadter). -export([main/0]). -define(MAX, 100000).   flip(V2, V1) when V1 > V2 -> 1; flip(_V2, _V1) -> 0.   list_terms(N, N, Acc) -> io:format("~w~n", [array:get(N, Acc)]); list_terms(Max, N, Acc) -> io:format("~w...
http://rosettacode.org/wiki/Hickerson_series_of_almost_integers
Hickerson series of almost integers
The following function,   due to D. Hickerson,   is said to generate "Almost integers" by the "Almost Integer" page of Wolfram MathWorld,   (December 31 2013).   (See formula numbered   51.) The function is:           h ( n ) = n ! 2 ( ln ⁡ 2 ) n + 1 {\displaystyle h(n)={\operatorname {n} ! \ove...
#Python
Python
from decimal import Decimal import math   def h(n): 'Simple, reduced precision calculation' return math.factorial(n) / (2 * math.log(2) ** (n + 1))   def h2(n): 'Extended precision Hickerson function' return Decimal(math.factorial(n)) / (2 * Decimal(2).ln() ** (n + 1))   for n in range(18): x = h2(n...
http://rosettacode.org/wiki/Hickerson_series_of_almost_integers
Hickerson series of almost integers
The following function,   due to D. Hickerson,   is said to generate "Almost integers" by the "Almost Integer" page of Wolfram MathWorld,   (December 31 2013).   (See formula numbered   51.) The function is:           h ( n ) = n ! 2 ( ln ⁡ 2 ) n + 1 {\displaystyle h(n)={\operatorname {n} ! \ove...
#Racket
Racket
#lang racket (require math/bigfloat)   (define (hickerson n) (bf/ (bffactorial n) 2.bf (bfexpt (bflog 2.bf) (bf (+ n 1)))))   (for ([n (in-range 18)]) (define hickerson-n (hickerson n)) (define first-decimal (bigfloat->integer (bftruncate (bf* 10.bf (bffrac hickerson-n))))) (define almost-intege...
http://rosettacode.org/wiki/Hello_world/Text
Hello world/Text
Hello world/Text is part of Short Circuit's Console Program Basics selection. Task Display the string Hello world! on a text console. Related tasks   Hello world/Graphical   Hello world/Line Printer   Hello world/Newbie   Hello world/Newline omission   Hello world/Standard error   Hello world/Web server
#8086_Assembly
8086 Assembly
DOSSEG .MODEL TINY .DATA TXT DB "Hello world!$" .CODE START: MOV ax, @DATA MOV ds, ax   MOV ah, 09h ; prepare output function MOV dx, OFFSET TXT ; set offset INT 21h ; output string TXT   MOV AX, 4C00h ; go back to DOS INT 21h END START
http://rosettacode.org/wiki/Heronian_triangles
Heronian triangles
Hero's formula for the area of a triangle given the length of its three sides   a,   b,   and   c   is given by: A = s ( s − a ) ( s − b ) ( s − c ) , {\displaystyle A={\sqrt {s(s-a)(s-b)(s-c)}},} where   s   is half the perimeter of the triangle; that is, s = a + b + c 2 . {\displaystyle s...
#Factor
Factor
USING: accessors assocs backtrack combinators.extras combinators.short-circuit formatting io kernel locals math math.functions math.order math.parser math.ranges mirrors qw sequences sorting.slots ; IN: rosetta-code.heronian-triangles   TUPLE: triangle a b c area perimeter ;   :: area ( a b c -- x ) a b + c + 2 / :...
http://rosettacode.org/wiki/Higher-order_functions
Higher-order functions
Task Pass a function     as an argument     to another function. Related task   First-class functions
#Bracmat
Bracmat
( (plus=a b.!arg:(?a.?b)&!a+!b) & ( print = text a b func .  !arg:(?a.?b.(=?func).?text) & out$(str$(!text "(" !a "," !b ")=" func$(!a.!b))) ) & print$(3.7.'$plus.add) & print $ ( 3 . 7 . (=a b.!arg:(?a.?b)&!a*!b) . multiply ) );
http://rosettacode.org/wiki/Hello_world/Web_server
Hello world/Web server
The browser is the new GUI ! Task Serve our standard text   Goodbye, World!   to   http://localhost:8080/   so that it can be viewed with a web browser. The provided solution must start or implement a server that accepts multiple client connections and serves text as requested. Note that starting a web browser or...
#Go
Go
package main   import ( "fmt" "log" "net/http" )   func main() { http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) { fmt.Fprintln(w, "Goodbye, World!") }) log.Fatal(http.ListenAndServe(":8080", nil)) }  
http://rosettacode.org/wiki/Hello_world/Web_server
Hello world/Web server
The browser is the new GUI ! Task Serve our standard text   Goodbye, World!   to   http://localhost:8080/   so that it can be viewed with a web browser. The provided solution must start or implement a server that accepts multiple client connections and serves text as requested. Note that starting a web browser or...
#Haskell
Haskell
{-# LANGUAGE OverloadedStrings #-}   import Data.ByteString.Char8 () import Data.Conduit ( ($$), yield ) import Data.Conduit.Network ( ServerSettings(..), runTCPServer )   main :: IO () main = runTCPServer (ServerSettings 8080 "127.0.0.1") $ const (yield response $$) where response = "HTTP/1.0 200 OK\nContent-Length:...
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#M2000_Interpreter
M2000 Interpreter
  Module Checkit { a$={This is the first line This is the second line End bracket position declare indentation fortext (except for first line) } Report a$ ' print all lines, without space at the left } CheckIt  
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#Mathematica_.2F_Wolfram_Language
Mathematica / Wolfram Language
Print["Mathematica is an interesing language, with its strings being multiline by\ default when not back\ s\\ashed!"];
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#MATLAB
MATLAB
sprintf('%s\n',... 'line1 text',... ' line2 text',... ' line3 text',... ' line4 text')   sprintf('%s\n',... 'Usage: thingy [OPTIONS]',... ' -h Display this usage message',... ' -H hostname Hostname to connect to')
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#NewLISP
NewLISP
; here-document.lsp ; oofoe 2012-01-19 ; http://rosettacode.org/wiki/Here_document   (print (format [text] Blast it %s! I'm a %s, not a %s! --- %s [/text] "James" "magician" "doctor" "L. McCoy"))   (exit)
http://rosettacode.org/wiki/History_variables
History variables
Storing the history of objects in a program is a common task. Maintaining the history of an object in a program has traditionally required programmers either to write specific code for handling the historical data, or to use a library which supports history logging. History variables are variables in a programming la...
#REXX
REXX
/*REXX program demonstrates a method to track history of assignments to a REXX variable.*/ varSet!.=0 /*initialize the all of the VARSET!'s. */ call varSet 'fluid',min(0,-5/2,-1)  ; say 'fluid=' fluid call varSet 'fluid',3.14159  ; say 'fluid=' fluid call varSet ...
http://rosettacode.org/wiki/History_variables
History variables
Storing the history of objects in a program is a common task. Maintaining the history of an object in a program has traditionally required programmers either to write specific code for handling the historical data, or to use a library which supports history logging. History variables are variables in a programming la...
#Ruby
Ruby
foo_hist = [] trace_var(:$foo){|v| foo_hist.unshift(v)}   $foo = "apple" $foo = "pear" $foo = "banana"   p foo_hist # => ["banana", "pear", "apple"]  
http://rosettacode.org/wiki/Hofstadter_Figure-Figure_sequences
Hofstadter Figure-Figure sequences
These two sequences of positive integers are defined as: R ( 1 ) = 1   ;   S ( 1 ) = 2 R ( n ) = R ( n − 1 ) + S ( n − 1 ) , n > 1. {\displaystyle {\begin{aligned}R(1)&=1\ ;\ S(1)=2\\R(n)&=R(n-1)+S(n-1),\quad n>1.\end{aligned}}} The sequence S ( n ) {\displaystyle S(n)} is further...
#Nim
Nim
var cr = @[1] var cs = @[2]   proc extendRS = let x = cr[cr.high] + cs[cr.high] cr.add x for y in cs[cs.high] + 1 ..< x: cs.add y cs.add x + 1   proc ffr(n: int): int = assert n > 0 while n > cr.len: extendRS() cr[n - 1]   proc ffs(n: int): int = assert n > 0 while n > cs.len: extendRS() cs[n - 1]  ...
http://rosettacode.org/wiki/Hofstadter_Figure-Figure_sequences
Hofstadter Figure-Figure sequences
These two sequences of positive integers are defined as: R ( 1 ) = 1   ;   S ( 1 ) = 2 R ( n ) = R ( n − 1 ) + S ( n − 1 ) , n > 1. {\displaystyle {\begin{aligned}R(1)&=1\ ;\ S(1)=2\\R(n)&=R(n-1)+S(n-1),\quad n>1.\end{aligned}}} The sequence S ( n ) {\displaystyle S(n)} is further...
#Oforth
Oforth
tvar: R ListBuffer new 1 over add R put   tvar: S ListBuffer new 2 over add S put   : buildnext | r s current i | R at ->r S at ->s r last r size s at + dup ->current r add s last 1+ current 1- for: i [ i s add ] current 1+ s add ;   : ffr(n) while ( R at size n < ) [ buildnext ] n R at at ...
http://rosettacode.org/wiki/Horner%27s_rule_for_polynomial_evaluation
Horner's rule for polynomial evaluation
A fast scheme for evaluating a polynomial such as: − 19 + 7 x − 4 x 2 + 6 x 3 {\displaystyle -19+7x-4x^{2}+6x^{3}\,} when x = 3 {\displaystyle x=3\;} . is to arrange the computation as follows: ( ( ( ( 0 ) x + 6 ) x + ( − 4 ) ) x + 7 ) x + ( − 19 ) {\displaystyle ((((0)x+6)x+(-4))x...
#Mercury
Mercury
  :- module horner. :- interface. :- import_module io. :- pred main(io::di, io::uo) is det. :- implementation. :- import_module int, list, string.   main(!IO) :- io.format("%i\n", [i(horner(3, [-19, 7, -4, 6]))], !IO).   :- func horner(int, list(int)) = int.   horner(X, Cs) = list.foldr((func(C, Acc) = Acc * X + C)...
http://rosettacode.org/wiki/Horner%27s_rule_for_polynomial_evaluation
Horner's rule for polynomial evaluation
A fast scheme for evaluating a polynomial such as: − 19 + 7 x − 4 x 2 + 6 x 3 {\displaystyle -19+7x-4x^{2}+6x^{3}\,} when x = 3 {\displaystyle x=3\;} . is to arrange the computation as follows: ( ( ( ( 0 ) x + 6 ) x + ( − 4 ) ) x + 7 ) x + ( − 19 ) {\displaystyle ((((0)x+6)x+(-4))x...
#.D0.9C.D0.9A-61.2F52
МК-61/52
ИП0 1 + П0 ИПE ИПD * КИП0 + ПE ИП0 1 - x=0 04 ИПE С/П
http://rosettacode.org/wiki/Hilbert_curve
Hilbert curve
Task Produce a graphical or ASCII-art representation of a Hilbert curve of at least order 3.
#Perl
Perl
use SVG; use List::Util qw(max min);   use constant pi => 2 * atan2(1, 0);   # Compute the curve with a Lindemayer-system %rules = ( A => '-BF+AFA+FB-', B => '+AF-BFB-FA+' ); $hilbert = 'A'; $hilbert =~ s/([AB])/$rules{$1}/eg for 1..6;   # Draw the curve in SVG ($x, $y) = (0, 0); $theta = pi/2; $r = 5; ...
http://rosettacode.org/wiki/Honeycombs
Honeycombs
The task is to produce a matrix of 20 hexagon shaped widgets in a honeycomb arrangement. The matrix should be arranged in such a manner that there are five columns of four hexagons. The hexagons in columns one, three and five are aligned horizontally, whereas the hexagons in columns two and four occupy a lower position...
#XPL0
XPL0
include c:\cxpl\stdlib; \(color definitions, etc.)   proc DrawHexagon(X0, Y0, Side, Color); \Draw a filled hexagon centered at X0,Y0 int X0, Y0, Side, Color; int X, Y; for Y:= -Side*19/22 to +Side*19/22 do \19/22 aprox = sqrt(3.0)/2.0 for X:= -Side to +Side do if abs(X) + abs(Y)...
http://rosettacode.org/wiki/Holidays_related_to_Easter
Holidays related to Easter
Task Calculate the dates of:   Easter   Ascension Thursday   Pentecost   Trinity Sunday   Corpus Christi feast (for Catholic)   All Saints' Sunday (for Orthodox) As an example, calculate for the first year of each century from;   years     400   to   2100 CE   and for   years   2010   to   2020 CE. Note ...
#Kotlin
Kotlin
// version 1.1.2   import java.util.Calendar import java.util.GregorianCalendar   val holidayOffsets = listOf( "Easter" to 0, "Ascension" to 39, "Pentecost" to 49, "Trinity" to 56, "C/Christi" to 60 )   fun String.padCenter(n: Int): String { val len = this.length if (n <= len) return this...
http://rosettacode.org/wiki/Horizontal_sundial_calculations
Horizontal sundial calculations
Task Create a program that calculates the hour, sun hour angle, dial hour line angle from 6am to 6pm for an operator entered location. For example, the user is prompted for a location and inputs the latitude and longitude 4°57′S 150°30′W (4.95°S 150.5°W of Jules Verne's Lincoln Island, aka Ernest Legouve Reef), wit...
#Nim
Nim
import rdstdin, strutils, math, strformat   let lat = parseFloat readLineFromStdin "Enter latitude => " let lng = parseFloat readLineFromStdin "Enter longitude => " let med = parseFloat readLineFromStdin "Enter legal meridian => " echo ""   let slat = sin lat.degToRad echo &" sine of latitude: {slat:.3f...
http://rosettacode.org/wiki/Horizontal_sundial_calculations
Horizontal sundial calculations
Task Create a program that calculates the hour, sun hour angle, dial hour line angle from 6am to 6pm for an operator entered location. For example, the user is prompted for a location and inputs the latitude and longitude 4°57′S 150°30′W (4.95°S 150.5°W of Jules Verne's Lincoln Island, aka Ernest Legouve Reef), wit...
#Objeck
Objeck
  class Sundial { function : Main(args : String[]) ~ Nil { "Enter latitude: "->Print(); lat := System.IO.Console->ReadString()->ToFloat(); "Enter longitude: "->Print(); lng := System.IO.Console->ReadString()->ToFloat(); "Enter legal meridian: "->Print(); ref := System.IO.Console->ReadStrin...
http://rosettacode.org/wiki/Huffman_coding
Huffman coding
Huffman encoding is a way to assign binary codes to symbols that reduces the overall number of bits used to encode a typical string of those symbols. For example, if you use letters as symbols and have details of the frequency of occurrence of those letters in typical strings, then you could just encode each letter wi...
#PL.2FI
PL/I
*process source attributes xref or(!); hencode: Proc Options(main); /*-------------------------------------------------------------------- * 28.12.013 Walter Pachl translated from REXX *-------------------------------------------------------------------*/ Dcl debug Bit(1) Init('0'b); Dcl (i,j,k) Bin Fixed(15); ...
http://rosettacode.org/wiki/Identity_matrix
Identity matrix
Task Build an   identity matrix   of a size known at run-time. An identity matrix is a square matrix of size n × n, where the diagonal elements are all 1s (ones), and all the other elements are all 0s (zeroes). I n = [ 1 0 0 ⋯ 0 0 1 0 ⋯ 0 0 0 1 ⋯ 0 ⋮ ⋮ ⋮ ⋱ ...
#Seed7
Seed7
$ include "seed7_05.s7i";   const type: matrix is array array integer;   const func matrix: identity (in integer: size) is func result var matrix: identity is matrix.value; local var integer: index is 0; begin identity := size times size times 0; for index range 1 to size do identity[index][...
http://rosettacode.org/wiki/Integer_comparison
Integer comparison
Basic Data Operation This is a basic data operation. It represents a fundamental action on a basic data type. You may see other such operations in the Basic Data Operations category, or: Integer Operations Arithmetic | Comparison Boolean Operations Bitwise | Logical String Operations Concatenation | Interpolation |...
#Seed7
Seed7
$ include "seed7_05.s7i";   const proc: main is func local var integer: a is 0; var integer: b is 0; begin readln(a); readln(b);   if a < b then writeln(a <& " is less than " <& b); end if;   if a = b then writeln(a <& " is equal to " <& b); end if;   if a > b then ...
http://rosettacode.org/wiki/Integer_comparison
Integer comparison
Basic Data Operation This is a basic data operation. It represents a fundamental action on a basic data type. You may see other such operations in the Basic Data Operations category, or: Integer Operations Arithmetic | Comparison Boolean Operations Bitwise | Logical String Operations Concatenation | Interpolation |...
#SenseTalk
SenseTalk
Ask "Provide Any Number"   Put It into A   Ask " Provide Another Number"   Put it into B   if A is less than B Put A&" Is less than " &B end if   if A is greater than B Put A& " is Greater than " &B end if   If A is Equal to B Put A& " is Equal to " &B End If
http://rosettacode.org/wiki/HTTP
HTTP
Task Access and print a URL's content (the located resource) to the console. There is a separate task for HTTPS Requests.
#Halon
Halon
echo http("http://www.rosettacode.org");
http://rosettacode.org/wiki/HTTP
HTTP
Task Access and print a URL's content (the located resource) to the console. There is a separate task for HTTPS Requests.
#Haskell
Haskell
  import Network.Browser import Network.HTTP import Network.URI   main = do rsp <- Network.Browser.browse $ do setAllowRedirects True setOutHandler $ const (return ()) request $ getRequest "http://www.rosettacode.org/" putStrLn $ rspBody $ snd rsp  
http://rosettacode.org/wiki/Hofstadter-Conway_$10,000_sequence
Hofstadter-Conway $10,000 sequence
The definition of the sequence is colloquially described as:   Starting with the list [1,1],   Take the last number in the list so far: 1, I'll call it x.   Count forward x places from the beginning of the list to find the first number to add (1)   Count backward x places from the end of the list to find the secon...
#Kotlin
Kotlin
// version 1.1.2   fun main(args: Array<String>) { val limit = (1 shl 20) + 1 val a = IntArray(limit) a[1] = 1 a[2] = 1 for (n in 3 until limit) { val p = a[n - 1] a[n] = a[p] + a[n - p] }   println(" Range Maximum") println("---------------- --------") ...
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#Fantom
Fantom
  class Main { public static Void main () { Env.cur.err.printLine ("Goodbye, World!") } }  
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#Forth
Forth
outfile-id stderr to outfile-id ." Goodbye, World!" cr to outfile-id
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#Fortran
Fortran
program StdErr ! Fortran 2003 use iso_fortran_env   ! in case there's no module iso_fortran_env ... !integer, parameter :: ERROR_UNIT = 0   write (ERROR_UNIT, *) "Goodbye, World!" end program StdErr
http://rosettacode.org/wiki/Hello_world/Standard_error
Hello world/Standard error
Hello world/Standard error is part of Short Circuit's Console Program Basics selection. A common practice in computing is to send error messages to a different output stream than normal text console messages. The normal messages print to what is called "standard output" or "standard out". The error messages print to ...
#FreeBASIC
FreeBASIC
' FB 1.05.0 Win64   Open Err As #1 Print #1, "Goodbye World!" Close #1 Sleep
http://rosettacode.org/wiki/Hofstadter_Q_sequence
Hofstadter Q sequence
Hofstadter Q sequence Q ( 1 ) = Q ( 2 ) = 1 , Q ( n ) = Q ( n − Q ( n − 1 ) ) + Q ( n − Q ( n − 2 ) ) , n > 2. {\displaystyle {\begin{aligned}Q(1)&=Q(2)=1,\\Q(n)&=Q{\big (}n-Q(n-1){\big )}+Q{\big (}n-Q(n-2){\big )},\quad n>2.\end{aligned}}} It is defined like the Fibonacc...
#ERRE
ERRE
  PROGRAM HOFSTADER_Q   ! ! for rosettacode.org !   DIM Q%[10000]   PROCEDURE QSEQUENCE(Q,FLAG%->SEQ$) ! if FLAG% is true accumulate sequence in SEQ$ ! (attention to string var lenght=255) ! otherwise calculate values in Q%[] only   LOCAL N Q%[1]=1 Q%[2]=1 SEQ$="1 1" IF NOT FLAG% THEN Q=NUM END IF FOR N=3 T...
http://rosettacode.org/wiki/Hofstadter_Q_sequence
Hofstadter Q sequence
Hofstadter Q sequence Q ( 1 ) = Q ( 2 ) = 1 , Q ( n ) = Q ( n − Q ( n − 1 ) ) + Q ( n − Q ( n − 2 ) ) , n > 2. {\displaystyle {\begin{aligned}Q(1)&=Q(2)=1,\\Q(n)&=Q{\big (}n-Q(n-1){\big )}+Q{\big (}n-Q(n-2){\big )},\quad n>2.\end{aligned}}} It is defined like the Fibonacc...
#F.23
F#
  // Populate an array with values of Hofstadter Q sequence. Nigel Galloway: August 26th., 2020 let fQ N=let g=Array.length N in N.[0]<-1; N.[1]<-1;(for g in 2..g-1 do N.[g]<-N.[g-N.[g-1]]+N.[g-N.[g-2]])  
http://rosettacode.org/wiki/Hickerson_series_of_almost_integers
Hickerson series of almost integers
The following function,   due to D. Hickerson,   is said to generate "Almost integers" by the "Almost Integer" page of Wolfram MathWorld,   (December 31 2013).   (See formula numbered   51.) The function is:           h ( n ) = n ! 2 ( ln ⁡ 2 ) n + 1 {\displaystyle h(n)={\operatorname {n} ! \ove...
#Raku
Raku
constant ln2 = [+] (1/2.FatRat, */2 ... *) Z/ 1 .. 100; constant h = [\*] 1/2, |(1..*) X/ ln2;   use Test; plan *;   for h[1..17] { ok m/'.'<[09]>/, .round(0.001) }
http://rosettacode.org/wiki/Hickerson_series_of_almost_integers
Hickerson series of almost integers
The following function,   due to D. Hickerson,   is said to generate "Almost integers" by the "Almost Integer" page of Wolfram MathWorld,   (December 31 2013).   (See formula numbered   51.) The function is:           h ( n ) = n ! 2 ( ln ⁡ 2 ) n + 1 {\displaystyle h(n)={\operatorname {n} ! \ove...
#REXX
REXX
/* REXX --------------------------------------------------------------- * 04.01.2014 Walter Pachl - using a rather aged ln function of mine * with probably unreasonably high precision * 05.01.2014 added n=18 *--------------------------------------------------------------------*/ Numeric Digits...
http://rosettacode.org/wiki/Hello_world/Text
Hello world/Text
Hello world/Text is part of Short Circuit's Console Program Basics selection. Task Display the string Hello world! on a text console. Related tasks   Hello world/Graphical   Hello world/Line Printer   Hello world/Newbie   Hello world/Newline omission   Hello world/Standard error   Hello world/Web server
#8th
8th
"Hello world!\n" . bye
http://rosettacode.org/wiki/Heronian_triangles
Heronian triangles
Hero's formula for the area of a triangle given the length of its three sides   a,   b,   and   c   is given by: A = s ( s − a ) ( s − b ) ( s − c ) , {\displaystyle A={\sqrt {s(s-a)(s-b)(s-c)}},} where   s   is half the perimeter of the triangle; that is, s = a + b + c 2 . {\displaystyle s...
#Fortran
Fortran
  MODULE GREEK MATHEMATICIANS !Two millenia back and more. CONTAINS INTEGER FUNCTION GCD(I,J) !Greatest common divisor. INTEGER I,J !Of these two integers. INTEGER N,M,R !Workers. N = MAX(I,J) !Since I don't want to damage I or J, M = MIN(I,J) !These copies mig...
http://rosettacode.org/wiki/Higher-order_functions
Higher-order functions
Task Pass a function     as an argument     to another function. Related task   First-class functions
#Brat
Brat
add = { a, b | a + b }   doit = { f, a, b | f a, b }   p doit ->add 1 2 #prints 3
http://rosettacode.org/wiki/Hello_world/Web_server
Hello world/Web server
The browser is the new GUI ! Task Serve our standard text   Goodbye, World!   to   http://localhost:8080/   so that it can be viewed with a web browser. The provided solution must start or implement a server that accepts multiple client connections and serves text as requested. Note that starting a web browser or...
#Io
Io
  WebRequest := Object clone do( handleSocket := method(aSocket, aSocket streamWrite("Goodbye, World!") aSocket close ) )   WebServer := Server clone do( setPort(8080) handleSocket := method(aSocket, WebRequest clone asyncSend(handleSocket(aSocket)) ) )   WebServer start  
http://rosettacode.org/wiki/Hello_world/Web_server
Hello world/Web server
The browser is the new GUI ! Task Serve our standard text   Goodbye, World!   to   http://localhost:8080/   so that it can be viewed with a web browser. The provided solution must start or implement a server that accepts multiple client connections and serves text as requested. Note that starting a web browser or...
#J
J
'Goodbye, World!'
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#Nim
Nim
echo """Usage: thingy [OPTIONS] -h Display this usage message -H hostname Hostname to connect to """
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#NMAKE.EXE
NMAKE.EXE
target0: dependent0 command0 << temporary, discarded inline file ... <<   target1: dependent1 command1 << temporary, but preserved inline file ... <<KEEP   target2: dependent2 command2 <<filename2 named, but discarded inline file ... <<NOKEEP   target3: dependent3 command3 <<filename3 named and preserve...
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#OCaml
OCaml
  print_string {whatever| 'hahah', `this` <is> \a\ "Heredoc" ${example} in OCaml |whatever} ;;  
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#OxygenBasic
OxygenBasic
s=quote """" She said "He said 'I said `There is a rumour going around.` ' " """" print s
http://rosettacode.org/wiki/History_variables
History variables
Storing the history of objects in a program is a common task. Maintaining the history of an object in a program has traditionally required programmers either to write specific code for handling the historical data, or to use a library which supports history logging. History variables are variables in a programming la...
#Rust
Rust
#[derive(Clone, Debug)] struct HVar<T> { history: Vec<T>, current: T, }   impl<T> HVar<T> { fn new(val: T) -> Self { HVar { history: Vec::new(), current: val, } }   fn get(&self) -> &T { &self.current }   fn set(&mut self, val: T) { sel...
http://rosettacode.org/wiki/History_variables
History variables
Storing the history of objects in a program is a common task. Maintaining the history of an object in a program has traditionally required programmers either to write specific code for handling the historical data, or to use a library which supports history logging. History variables are variables in a programming la...
#Scala
Scala
class HVar[A](initialValue: A) extends Proxy { override def self = !this override def toString = "HVar(" + !this + ")"   def history = _history   private var _history = List(initialValue) def unary_! = _history.head def :=(newValue: A): Unit = { _history = newValue :: _history } def modify(f: A => A...
http://rosettacode.org/wiki/Hofstadter_Figure-Figure_sequences
Hofstadter Figure-Figure sequences
These two sequences of positive integers are defined as: R ( 1 ) = 1   ;   S ( 1 ) = 2 R ( n ) = R ( n − 1 ) + S ( n − 1 ) , n > 1. {\displaystyle {\begin{aligned}R(1)&=1\ ;\ S(1)=2\\R(n)&=R(n-1)+S(n-1),\quad n>1.\end{aligned}}} The sequence S ( n ) {\displaystyle S(n)} is further...
#Perl
Perl
#!perl use strict; use warnings;   my @r = ( undef, 1 ); my @s = ( undef, 2 );   sub ffsr { my $n = shift; while( $#r < $n ) { push @r, $s[$#r]+$r[-1]; push @s, grep { $s[-1]<$_ } $s[-1]+1..$r[-1]-1, $r[-1]+1; } return $n; }   sub ffr { $r[ffsr shift] } sub ffs { $s[ffsr shift] }   printf " i: R(i) S(i...
http://rosettacode.org/wiki/Horner%27s_rule_for_polynomial_evaluation
Horner's rule for polynomial evaluation
A fast scheme for evaluating a polynomial such as: − 19 + 7 x − 4 x 2 + 6 x 3 {\displaystyle -19+7x-4x^{2}+6x^{3}\,} when x = 3 {\displaystyle x=3\;} . is to arrange the computation as follows: ( ( ( ( 0 ) x + 6 ) x + ( − 4 ) ) x + 7 ) x + ( − 19 ) {\displaystyle ((((0)x+6)x+(-4))x...
#Modula-2
Modula-2
MODULE Horner; FROM RealStr IMPORT RealToStr; FROM Terminal IMPORT WriteString,WriteLn,ReadChar;   PROCEDURE Horner(coeff : ARRAY OF REAL; x : REAL) : REAL; VAR ans : REAL; i : CARDINAL; BEGIN ans := 0.0; FOR i:=HIGH(coeff) TO 0 BY -1 DO ans := (ans * x) + coeff[i]; END; RETURN ans END H...
http://rosettacode.org/wiki/Horner%27s_rule_for_polynomial_evaluation
Horner's rule for polynomial evaluation
A fast scheme for evaluating a polynomial such as: − 19 + 7 x − 4 x 2 + 6 x 3 {\displaystyle -19+7x-4x^{2}+6x^{3}\,} when x = 3 {\displaystyle x=3\;} . is to arrange the computation as follows: ( ( ( ( 0 ) x + 6 ) x + ( − 4 ) ) x + 7 ) x + ( − 19 ) {\displaystyle ((((0)x+6)x+(-4))x...
#NetRexx
NetRexx
/* NetRexx */ options replace format comments java crossref savelog symbols nobinary   c = [-19, 7, -4, 6] -- # list coefficients of all x^0..x^n in order n=3 x=3 r=0 loop i=n to 0 by -1 r=r*x+c[i] End Say r Say 6*x**3-4*x**2+7*x-19
http://rosettacode.org/wiki/Hilbert_curve
Hilbert curve
Task Produce a graphical or ASCII-art representation of a Hilbert curve of at least order 3.
#Phix
Phix
-- -- demo\rosetta\hilbert_curve.exw -- ============================== -- -- Draws a hilbert curve. -- with javascript_semantics include pGUI.e constant title = "Hilbert Curve" Ihandle dlg, canvas cdCanvas cddbuffer, cdcanvas constant width = 64 sequence points = {} procedure hilbert(integer x, y, lg, i1, i2) ...
http://rosettacode.org/wiki/Holidays_related_to_Easter
Holidays related to Easter
Task Calculate the dates of:   Easter   Ascension Thursday   Pentecost   Trinity Sunday   Corpus Christi feast (for Catholic)   All Saints' Sunday (for Orthodox) As an example, calculate for the first year of each century from;   years     400   to   2100 CE   and for   years   2010   to   2020 CE. Note ...
#Lua
Lua
local Time = require("time")   function div (x, y) return math.floor(x / y) end   function easter (year) local G = year % 19 local C = div(year, 100) local H = (C - div(C, 4) - div((8 * C + 13), 25) + 19 * G + 15) % 30 local I = H - div(H, 28) * (1 - div(29, H + 1)) * (div(21 - G, 11)) local J = (ye...
http://rosettacode.org/wiki/Horizontal_sundial_calculations
Horizontal sundial calculations
Task Create a program that calculates the hour, sun hour angle, dial hour line angle from 6am to 6pm for an operator entered location. For example, the user is prompted for a location and inputs the latitude and longitude 4°57′S 150°30′W (4.95°S 150.5°W of Jules Verne's Lincoln Island, aka Ernest Legouve Reef), wit...
#OCaml
OCaml
let () = let pi = 4. *. atan 1. in print_endline "Enter latitude => "; let lat = read_float () in print_endline "Enter longitude => "; let lng = read_float () in print_endline "Enter legal meridian => "; let ref = read_float () in print_newline ();   let slat = sin (lat *. 2. *. pi /. 360.) in Prin...
http://rosettacode.org/wiki/Huffman_coding
Huffman coding
Huffman encoding is a way to assign binary codes to symbols that reduces the overall number of bits used to encode a typical string of those symbols. For example, if you use letters as symbols and have details of the frequency of occurrence of those letters in typical strings, then you could just encode each letter wi...
#PowerShell
PowerShell
  function Get-HuffmanEncodingTable ( $String ) { # Create leaf nodes $ID = 0 $Nodes = [char[]]$String | Group-Object | ForEach { $ID++; $_ } | Select @{ Label = 'Symbol'  ; Expression = { $_.Name } }, @{ Label = 'Count'  ; Expression = { $_.Count } }, ...
http://rosettacode.org/wiki/Identity_matrix
Identity matrix
Task Build an   identity matrix   of a size known at run-time. An identity matrix is a square matrix of size n × n, where the diagonal elements are all 1s (ones), and all the other elements are all 0s (zeroes). I n = [ 1 0 0 ⋯ 0 0 1 0 ⋯ 0 0 0 1 ⋯ 0 ⋮ ⋮ ⋮ ⋱ ...
#SenseTalk
SenseTalk
  set matrix to buildIdentityMatrix(3)   repeat for each item in matrix put it end repeat   set matrix to buildIdentityMatrix(17)   repeat for each item in matrix put it end repeat   function buildIdentityMatrix matrixSize set matrixList to () repeat matrixSize times set rowMatrixIndex to the counter set rowMat...