task_url stringlengths 30 116 | task_name stringlengths 2 86 | task_description stringlengths 0 14.4k | language_url stringlengths 2 53 | language_name stringlengths 1 52 | code stringlengths 0 61.9k |
|---|---|---|---|---|---|
http://rosettacode.org/wiki/Enumerations | Enumerations | Task
Create an enumeration of constants with and without explicit values.
| #D | D | void main() {
// Named enumeration (commonly used enum in D).
// The underlying type is a 32 bit int.
enum Fruits1 { apple, banana, cherry }
// You can assign an enum to the general type, but not the opposite:
int f1 = Fruits1.banana; // No error.
// Fruits1 f2 = 1; // Error: cannot implicitly... |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #Clojure | Clojure | user> (def d [1 2 3 4 5]) ; immutable vector
#'user/d
user> (assoc d 3 7)
[1 2 3 7 5]
user> d
[1 2 3 4 5] |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #COBOL | COBOL | ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SPECIAL-NAMES.
SYMBOLIC CHARACTERS NUL IS 0, TAB IS 9. |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #D | D | import std.random;
// enum allows to define manifest (compile-time) constants:
int sqr(int x) { return x ^^ 2; }
enum int x = 5;
enum y = sqr(5); // Forces Compile-Time Function Evaluation (CTFE).
// enums are compile-time constants:
enum MyEnum { A, B, C }
// immutable defines values that can't change:
immutab... |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #Aime | Aime | integer c;
real h, v;
index x;
data s;
for (, c in (s = argv(1))) {
x[c] += 1r;
}
h = 0;
for (, v in x) {
v /= ~s;
h -= v * log2(v);
}
o_form("/d6/\n", h); |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #ALGOL_68 | ALGOL 68 | BEGIN
# calculate the shannon entropy of a string #
PROC shannon entropy = ( STRING s )REAL:
BEGIN
INT string length = ( UPB s - LWB s ) + 1;
# count the occurences of each character #
[ 0 : max abs char ]INT char count;
FOR char pos FROM LWB ch... |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last ... | #AWK | AWK | function halve(x)
{
return int(x/2)
}
function double(x)
{
return x*2
}
function iseven(x)
{
return x%2 == 0
}
function ethiopian(plier, plicand)
{
r = 0
while(plier >= 1) {
if ( !iseven(plier) ) {
r += plicand
}
plier = halve(plier)
plicand = double(plicand)
}
return r
}
BEG... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Clojure | Clojure | (defn equilibrium [lst]
(loop [acc '(), i 0, left 0, right (apply + lst), lst lst]
(if (empty? lst)
(reverse acc)
(let [[x & xs] lst
right (- right x)
acc (if (= left right) (cons i acc) acc)]
(recur acc (inc i) (+ left x) right xs))))) |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Common_Lisp | Common Lisp | (defun dflt-on-nil (v dflt)
(if v v dflt))
(defun eq-index (v)
(do*
((stack nil)
(i 0 (+ 1 i))
(rest v (cdr rest))
(lsum 0)
(rsum (apply #'+ (cdr v))))
;; Reverse here is not strictly necessary
((null rest) (reverse stack))
(if (eql lsum rsum) (push i stack... |
http://rosettacode.org/wiki/Environment_variables | Environment variables | Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
PATH
HOME
USER
| #FreeBASIC | FreeBASIC | ' FB 1.05.0 Win64
Var v = Environ("SystemRoot")
Print v
Sleep |
http://rosettacode.org/wiki/Environment_variables | Environment variables | Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
PATH
HOME
USER
| #Frink | Frink | callJava["java.lang.System", "getenv", ["HOME"]] |
http://rosettacode.org/wiki/Environment_variables | Environment variables | Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
PATH
HOME
USER
| #FunL | FunL | println( System.getenv('PATH') )
println( $home )
println( $user ) |
http://rosettacode.org/wiki/Esthetic_numbers | Esthetic numbers | An esthetic number is a positive integer where every adjacent digit differs from its neighbour by 1.
E.G.
12 is an esthetic number. One and two differ by 1.
5654 is an esthetic number. Each digit is exactly 1 away from its neighbour.
890 is not an esthetic number. Nine and zero differ by 9.
These examples are n... | #Phix | Phix | constant aleph = "0123456789ABCDEF"
function efill(string s, integer ch, i)
-- min-fill, like 10101 or 54321 or 32101
s[i] = ch
for j=i+1 to length(s) do
ch = iff(ch>='1'?iff(ch='A'?'9':ch-1):'1')
s[j] = ch
end for
return s
end function
function esthetic(string s, integer base = ... |
http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture | Euler's sum of powers conjecture | There is a conjecture in mathematics that held for over two hundred years before it was disproved by the finding of a counterexample in 1966 by Lander and Parkin.
Euler's (disproved) sum of powers conjecture
At least k positive kth powers are required to sum to a kth power,
except for the trivial case... | #Delphi | Delphi | n = 250
len p5[] n
len h5[] 65537
for i range n
p5[i] = i * i * i * i * i
h5[p5[i] mod 65537] = 1
.
func search a s . y .
y = -1
b = n
while a + 1 < b
i = (a + b) div 2
if p5[i] > s
b = i
elif p5[i] < s
a = i
else
a = b
y = i
.
.
.
for x0 range n
for x1 range x0... |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterat... | #MUMPS | MUMPS | factorial(num) New ii,result
If num<0 Quit "Negative number"
If num["." Quit "Not an integer"
Set result=1 For ii=1:1:num Set result=result*ii
Quit result
Write $$factorial(0) ; 1
Write $$factorial(1) ; 1
Write $$factorial(2) ; 2
Write $$factorial(3) ; 6
Write $$factorial(10) ; 3628800
Write $$factorial(-6) ; Neg... |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #BASIC | BASIC | 10 INPUT "ENTER A NUMBER: ";N
20 IF N/2 <> INT(N/2) THEN PRINT "THE NUMBER IS ODD":GOTO 40
30 PRINT "THE NUMBER IS EVEN"
40 END |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #Batch_File | Batch File |
@echo off
set /p i=Insert number:
::bitwise and
set /a "test1=%i%&1"
::divide last character by 2
set /a test2=%i:~-1%/2
::modulo
set /a test3=%i% %% 2
set test
pause>nul
|
http://rosettacode.org/wiki/Euler_method | Euler method | Euler's method numerically approximates solutions of first-order ordinary differential equations (ODEs) with a given initial value. It is an explicit method for solving initial value problems (IVPs), as described in the wikipedia page.
The ODE has to be provided in the following form:
d
y
(
t
)
d
t
=
f... | #Oforth | Oforth | : euler(f, y, a, b, h)
| t |
a b h step: t [
System.Out t <<wjp(6, JUSTIFY_RIGHT, 3) " : " << y << cr
t y f perform h * y + ->y
] ; |
http://rosettacode.org/wiki/Euler_method | Euler method | Euler's method numerically approximates solutions of first-order ordinary differential equations (ODEs) with a given initial value. It is an explicit method for solving initial value problems (IVPs), as described in the wikipedia page.
The ODE has to be provided in the following form:
d
y
(
t
)
d
t
=
f... | #Pascal | Pascal |
{$mode delphi}
PROGRAM Euler;
TYPE TNewtonCooling = FUNCTION (t: REAL) : REAL;
CONST T0 : REAL = 100.0;
CONST TR : REAL = 20.0;
CONST k : REAL = 0.07;
CONST time : INTEGER = 100;
CONST step : INTEGER = 10;
CONST dt : ARRAY[0..3] of REAL = (1.0,2.0,5.0,10.0);
VAR i : INTEGER;
FUNCTION NewtonCooling(... |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #FreeBASIC | FreeBASIC | ' FB 1.05.0 Win64
Function factorial(n As Integer) As Integer
If n < 1 Then Return 1
Dim product As Integer = 1
For i As Integer = 2 To n
product *= i
Next
Return Product
End Function
Function binomial(n As Integer, k As Integer) As Integer
If n < 0 OrElse k < 0 OrElse n <= k Then Return 1
Dim pro... |
http://rosettacode.org/wiki/Fibonacci_sequence | Fibonacci sequence | The Fibonacci sequence is a sequence Fn of natural numbers defined recursively:
F0 = 0
F1 = 1
Fn = Fn-1 + Fn-2, if n>1
Task
Write a function to generate the nth Fibonacci number.
Solutions can be iterative or recursive (though recursive solutions are generally considered too slow ... | #x86_Assembly | x86 Assembly | TITLE i hate visual studio 4 (Fibs.asm)
; __ __/--------\
; >__ \ / | |\
; \ \___/ @ \ / \__________________
; \____ \ / \\\
; \____ Coded with love by: |||
; \ Alexander Alvon... |
http://rosettacode.org/wiki/Entropy/Narcissist | Entropy/Narcissist |
Task
Write a computer program that computes and shows its own entropy.
Related Tasks
Fibonacci_word
Entropy
| #Phix | Phix | without js -- command_line, file i/o
function entropy(sequence s)
sequence symbols = {},
counts = {}
integer N = length(s)
for i=1 to N do
object si = s[i]
integer k = find(si,symbols)
if k=0 then
symbols = append(symbols,si)
counts = append(count... |
http://rosettacode.org/wiki/Entropy/Narcissist | Entropy/Narcissist |
Task
Write a computer program that computes and shows its own entropy.
Related Tasks
Fibonacci_word
Entropy
| #PHP | PHP | <?php
$h = 0;
$s = file_get_contents(__FILE__);
$l = strlen($s);
foreach ( count_chars($s, 1) as $c )
$h -=
( $c / $l ) *
log( $c / $l, 2 );
echo $h; |
http://rosettacode.org/wiki/Enumerations | Enumerations | Task
Create an enumeration of constants with and without explicit values.
| #Delphi | Delphi | type
fruit = (apple, banana, cherry);
ape = (gorilla = 0, chimpanzee = 1, orangutan = 5); |
http://rosettacode.org/wiki/Enumerations | Enumerations | Task
Create an enumeration of constants with and without explicit values.
| #DWScript | DWScript | type TFruit = (Apple, Banana, Cherry);
type TApe = (Gorilla = 0, Chimpanzee = 1, Orangutan = 5); |
http://rosettacode.org/wiki/Empty_directory | Empty directory | Starting with a path to some directory, determine whether the directory is empty.
An empty directory contains no files nor subdirectories.
With Unix or Windows systems, every directory contains an entry for “.” and almost every directory contains “..” (except for a root directory); an empty directory contains no other... | #11l | 11l | I fs:list_dir(input()).empty
print(‘empty’)
E
print(‘not empty’) |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #Delphi | Delphi | const
STR1 = 'abc'; // regular constant
STR2: string = 'def'; // typed constant |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #Dyalect | Dyalect | let pi = 3.14
let helloWorld = "Hello, world!" |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #E | E | def x := 1
x := 2 # this is an error |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #Ela | Ela | open unsafe.cell
r = ref 0 |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #ALGOL_W | ALGOL W | begin
% calculates the shannon entropy of a string %
% strings are fixed length in algol W and the length is part of the %
% type, so we declare the string parameter to be the longest possible %
% string length (256 characters) and have a second parameter to %
% spec... |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #APL | APL |
ENTROPY←{-+/R×2⍟R←(+⌿⍵∘.=∪⍵)÷⍴⍵}
⍝ How it works:
⎕←UNIQUE←∪X←'1223334444'
1234
⎕←TABLE_OF_OCCURENCES←X∘.=UNIQUE
1 0 0 0
0 1 0 0
0 1 0 0
0 0 1 0
0 0 1 0
0 0 1 0
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
⎕←COUNT←+⌿TABLE_OF_OCCURENCES
1 2 3 4
⎕←N←⍴X
10
⎕←RATIO←COUNT÷N
0.1 0.2 0.3 0.4
... |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last ... | #BASIC | BASIC |
REM Ethiopian multiplication
X = 17
Y = 34
TOT = 0
WHILE X >= 1
PRINT X;
PRINT " ";
A = X
GOSUB CHECKEVEN:
IF ISEVEN = 0 THEN
TOT = TOT + Y
PRINT Y;
ENDIF
PRINT
A = X
GOSUB HALVE:
X = A
A = Y
GOSUB DOUBLE:
Y = A
WEND
PRINT "= ";
PRINT TOT
END
REM Subroutines are required, th... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #D | D | import std.stdio, std.algorithm, std.range, std.functional;
auto equilibrium(Range)(Range r) pure nothrow @safe /*@nogc*/ {
return r.length.iota.filter!(i => r[0 .. i].sum == r[i + 1 .. $].sum);
}
void main() {
[-7, 1, 5, 2, -4, 3, 0].equilibrium.writeln;
} |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Delphi | Delphi | import extensions;
import system'routines;
import system'collections;
import extensions'routines;
class EquilibriumEnumerator : Enumerator
{
int left;
int right;
int index;
Enumerator en;
constructor new(Enumerator en)
{
this en := en;
self.reset()
... |
http://rosettacode.org/wiki/Environment_variables | Environment variables | Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
PATH
HOME
USER
| #Go | Go | package main
import (
"fmt"
"os"
)
func main() {
fmt.Println(os.Getenv("SHELL"))
} |
http://rosettacode.org/wiki/Environment_variables | Environment variables | Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
PATH
HOME
USER
| #Gri | Gri | get env \foo HOME
show "\foo" |
http://rosettacode.org/wiki/Environment_variables | Environment variables | Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
PATH
HOME
USER
| #Groovy | Groovy | System.getenv().each { property, value -> println "$property = $value"} |
http://rosettacode.org/wiki/Esthetic_numbers | Esthetic numbers | An esthetic number is a positive integer where every adjacent digit differs from its neighbour by 1.
E.G.
12 is an esthetic number. One and two differ by 1.
5654 is an esthetic number. Each digit is exactly 1 away from its neighbour.
890 is not an esthetic number. Nine and zero differ by 9.
These examples are n... | #PicoLisp | PicoLisp | (de esthetic (N Base)
(let Lst
(make
(loop
(yoke (% N Base))
(T (=0 (setq N (/ N Base)))) ) )
(and
(fully
=1
(make
(for (L Lst (cdr L) (cdr L))
(link (abs (- (car L) (cadr L)))) ) ) )
(pack
... |
http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture | Euler's sum of powers conjecture | There is a conjecture in mathematics that held for over two hundred years before it was disproved by the finding of a counterexample in 1966 by Lander and Parkin.
Euler's (disproved) sum of powers conjecture
At least k positive kth powers are required to sum to a kth power,
except for the trivial case... | #EasyLang | EasyLang | n = 250
len p5[] n
len h5[] 65537
for i range n
p5[i] = i * i * i * i * i
h5[p5[i] mod 65537] = 1
.
func search a s . y .
y = -1
b = n
while a + 1 < b
i = (a + b) div 2
if p5[i] > s
b = i
elif p5[i] < s
a = i
else
a = b
y = i
.
.
.
for x0 range n
for x1 range x0... |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterat... | #MyrtleScript | MyrtleScript | func factorial args: int a : returns: int {
int factorial = a
repeat int i = (a - 1) : i == 0 : i-- {
factorial *= i
}
return factorial
} |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #BBC_BASIC | BBC BASIC | IF FNisodd%(14) PRINT "14 is odd" ELSE PRINT "14 is even"
IF FNisodd%(15) PRINT "15 is odd" ELSE PRINT "15 is even"
IF FNisodd#(9876543210#) PRINT "9876543210 is odd" ELSE PRINT "9876543210 is even"
IF FNisodd#(9876543211#) PRINT "9876543211 is odd" ELSE PRINT "9876543211 is even"
END
... |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #bc | bc | i = -3
/* Assumes that i is an integer. */
scale = 0
if (i % 2 == 0) "i is even
"
if (i % 2) "i is odd
" |
http://rosettacode.org/wiki/Euler_method | Euler method | Euler's method numerically approximates solutions of first-order ordinary differential equations (ODEs) with a given initial value. It is an explicit method for solving initial value problems (IVPs), as described in the wikipedia page.
The ODE has to be provided in the following form:
d
y
(
t
)
d
t
=
f... | #Perl | Perl | sub euler_method {
my ($t0, $t1, $k, $step_size) = @_;
my @results = ( [0, $t0] );
for (my $s = $step_size; $s <= 100; $s += $step_size) {
$t0 -= ($t0 - $t1) * $k * $step_size;
push @results, [$s, $t0];
}
return @results;
}
sub analytical {
... |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #Frink | Frink |
println[binomial[5,3]]
|
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #FunL | FunL | def
choose( n, k ) | k < 0 or k > n = 0
choose( n, 0 ) = 1
choose( n, n ) = 1
choose( n, k ) = product( [(n - i)/(i + 1) | i <- 0:min( k, n - k )] )
println( choose(5, 3) )
println( choose(60, 30) ) |
http://rosettacode.org/wiki/Fibonacci_sequence | Fibonacci sequence | The Fibonacci sequence is a sequence Fn of natural numbers defined recursively:
F0 = 0
F1 = 1
Fn = Fn-1 + Fn-2, if n>1
Task
Write a function to generate the nth Fibonacci number.
Solutions can be iterative or recursive (though recursive solutions are generally considered too slow ... | #xEec | xEec |
h#1 h#1 h#1 o#
h#10 o$ p
>f
o# h#10 o$ p
ma h? jnext p
t
jnf
|
http://rosettacode.org/wiki/Entropy/Narcissist | Entropy/Narcissist |
Task
Write a computer program that computes and shows its own entropy.
Related Tasks
Fibonacci_word
Entropy
| #Picat | Picat |
entropy(File) = E =>
Bytes = read_file_bytes(File),
F = [0: I in 1..256],
foreach (B in Bytes)
B1 := B + 1,
F[B1] := F[B1] + 1
end,
HM = 0,
foreach (C in F)
if (C > 0) then
HM := HM + C * log(2, C)
end
end,
L = Bytes.length,
E = log(2, L)... |
http://rosettacode.org/wiki/Entropy/Narcissist | Entropy/Narcissist |
Task
Write a computer program that computes and shows its own entropy.
Related Tasks
Fibonacci_word
Entropy
| #PicoLisp | PicoLisp |
(scl 8)
(load "@lib/math.l")
(setq LN2 0.693147180559945309417)
(setq Me
(let F (file)
(pack (car F) (cadr F))))
(setq Hist NIL Sz 0)
(in Me
(use Ch
(while (setq Ch (rd 1))
(inc 'Sz)
(if (assoc Ch Hist)
(con @ (inc (cdr @)))
(setq Hist (cons (cons Ch 1... |
http://rosettacode.org/wiki/Entropy/Narcissist | Entropy/Narcissist |
Task
Write a computer program that computes and shows its own entropy.
Related Tasks
Fibonacci_word
Entropy
| #Python | Python | import math
from collections import Counter
def entropy(s):
p, lns = Counter(s), float(len(s))
return -sum( count/lns * math.log(count/lns, 2) for count in p.values())
with open(__file__) as f:
b=f.read()
print(entropy(b)) |
http://rosettacode.org/wiki/Entropy/Narcissist | Entropy/Narcissist |
Task
Write a computer program that computes and shows its own entropy.
Related Tasks
Fibonacci_word
Entropy
| #Racket | Racket |
#lang racket
(require math)
(define (log2 x) (/ (log x) (log 2)))
(define ds (string->list (file->string "entropy.rkt")))
(define n (length ds))
(- (for/sum ([(d c) (in-hash (samples->hash ds))])
(* (/ c n) (log2 (/ c n)))))
|
http://rosettacode.org/wiki/Enumerations | Enumerations | Task
Create an enumeration of constants with and without explicit values.
| #E | E | def apple { to value() { return 0 } }
def banana { to value() { return 1 } }
def cherry { to value() { return 2 } } |
http://rosettacode.org/wiki/Enumerations | Enumerations | Task
Create an enumeration of constants with and without explicit values.
| #EGL | EGL | // Without explicit values
enumeration FruitsKind
APPLE,
BANANA,
CHERRY
end
program EnumerationTest
function main()
whatFruitAmI(FruitsKind.CHERRY);
end
function whatFruitAmI(fruit FruitsKind)
case (fruit)
when(FruitsKind.APPLE)
syslib.writestdout("You're an apple.");
when(FruitsKind.BANANA)
... |
http://rosettacode.org/wiki/Enumerations | Enumerations | Task
Create an enumeration of constants with and without explicit values.
| #Elixir | Elixir | fruits = [:apple, :banana, :cherry]
fruits = ~w(apple banana cherry)a # Above-mentioned different notation
val = :banana
Enum.member?(fruits, val) #=> true
val in fruits #=> true |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #11l | 11l | V s = ‘’
I s.empty
print(‘String s is empty.’)
I !s.empty
print(‘String s is not empty.’) |
http://rosettacode.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm | Elliptic Curve Digital Signature Algorithm | Elliptic curves.
An elliptic curve E over ℤp (p ≥ 5) is defined by an equation of the form
y^2 = x^3 + ax + b, where a, b ∈ ℤp and the discriminant ≢ 0 (mod p),
together with a special point 𝒪 called the point at infinity.
The set E(ℤp) consists of all points (x, y), with x, y ∈ ℤp,
which satisfy the above defining eq... | #C | C |
/*
subject: Elliptic curve digital signature algorithm,
toy version for small modulus N.
tested : gcc 4.6.3, tcc 0.9.27
*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
// 64-bit integer type
typedef long long int dlong;
// rational ec point
typedef struct {
dlong x, y;
} epnt;
// elliptic cu... |
http://rosettacode.org/wiki/Empty_directory | Empty directory | Starting with a path to some directory, determine whether the directory is empty.
An empty directory contains no files nor subdirectories.
With Unix or Windows systems, every directory contains an entry for “.” and almost every directory contains “..” (except for a root directory); an empty directory contains no other... | #8086_Assembly | 8086 Assembly | ; this routine attempts to remove the directory and returns an error code if it cannot.
mov ax,seg dirname ;load into AX the segment where dirname is stored.
mov ds,ax ;load the segment register DS with the segment of dirname
mov dx,offset dirname ;load into DX the offset of dirnam... |
http://rosettacode.org/wiki/Empty_directory | Empty directory | Starting with a path to some directory, determine whether the directory is empty.
An empty directory contains no files nor subdirectories.
With Unix or Windows systems, every directory contains an entry for “.” and almost every directory contains “..” (except for a root directory); an empty directory contains no other... | #Ada | Ada | with Ada.Text_IO; use Ada.Text_IO;
with Ada.Directories;
procedure EmptyDir is
function Empty (path : String) return String is
use Ada.Directories;
result : String := "Is empty.";
procedure check (ent : Directory_Entry_Type) is begin
if Simple_Name (ent) /= "." and Simple_Name (ent) /= "..... |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #11l | 11l | BR 14
END |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #Elixir | Elixir | iex(1)> x = 10 # bind
10
iex(2)> 10 = x # Pattern matching
10
iex(3)> x = 20 # rebound
20
iex(4)> ^x = 10 # pin operator ^
** (MatchError) no match of right hand side value: 10
|
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #Erlang | Erlang | X = 10,
X = 20. |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #Euphoria | Euphoria | constant n = 1
constant s = {1,2,3}
constant str = "immutable string" |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #F.23 | F# | let hello = "Hello!" |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #Arturo | Arturo | entropy: function [s][
t: #[]
loop s 'c [
unless key? t c -> t\[c]: 0
t\[c]: t\[c] + 1
]
result: new 0
loop values t 'x ->
'result - (x//(size s)) * log x//(size s) 2
return result
]
print entropy "1223334444" |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #AutoHotkey | AutoHotkey | MsgBox, % Entropy(1223334444)
Entropy(n)
{
a := [], len := StrLen(n), m := n
while StrLen(m)
{
s := SubStr(m, 1, 1)
m := RegExReplace(m, s, "", c)
a[s] := c
}
for key, val in a
{
m := Log(p := val / len)
e -= p * m / Log(2)
}
return, e
} |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last ... | #Batch_File | Batch File |
@echo off
:: Pick 2 random, non-zero, 2-digit numbers to send to :_main
set /a param1=%random% %% 98 + 1
set /a param2=%random% %% 98 + 1
call:_main %param1% %param2%
pause>nul
exit /b
:: This is the main function that outputs the answer in the form of "%1 * %2 = %answer%"
:_main
setlocal enabledelayedexpansion
set ... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Elena | Elena | import extensions;
import system'routines;
import system'collections;
import extensions'routines;
class EquilibriumEnumerator : Enumerator
{
int left;
int right;
int index;
Enumerator en;
constructor new(Enumerator en)
{
this en := en;
self.reset()
... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Elixir | Elixir | defmodule Equilibrium do
def index(list) do
last = length(list)
Enum.filter(0..last-1, fn i ->
Enum.sum(Enum.slice(list, 0, i)) == Enum.sum(Enum.slice(list, i+1..last))
end)
end
end |
http://rosettacode.org/wiki/Environment_variables | Environment variables | Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
PATH
HOME
USER
| #Haskell | Haskell | import System.Environment
main = do getEnv "HOME" >>= print -- get env var
getEnvironment >>= print -- get the entire environment as a list of (key, value) pairs |
http://rosettacode.org/wiki/Environment_variables | Environment variables | Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
PATH
HOME
USER
| #hexiscript | hexiscript | println env "HOME"
println env "PATH"
println env "USER" |
http://rosettacode.org/wiki/Environment_variables | Environment variables | Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
PATH
HOME
USER
| #HicEst | HicEst | CHARACTER string*255
string = "PATH="
SYSTEM(GEteNV = string) |
http://rosettacode.org/wiki/Esthetic_numbers | Esthetic numbers | An esthetic number is a positive integer where every adjacent digit differs from its neighbour by 1.
E.G.
12 is an esthetic number. One and two differ by 1.
5654 is an esthetic number. Each digit is exactly 1 away from its neighbour.
890 is not an esthetic number. Nine and zero differ by 9.
These examples are n... | #Prolog | Prolog | main:-
forall(between(2, 16, Base),
(Min_index is Base * 4, Max_index is Base * 6,
print_esthetic_numbers1(Base, Min_index, Max_index))),
print_esthetic_numbers2(1000, 9999, 16),
nl,
print_esthetic_numbers2(100000000, 130000000, 8).
print_esthetic_numbers1(Base, Min_index, Max_... |
http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture | Euler's sum of powers conjecture | There is a conjecture in mathematics that held for over two hundred years before it was disproved by the finding of a counterexample in 1966 by Lander and Parkin.
Euler's (disproved) sum of powers conjecture
At least k positive kth powers are required to sum to a kth power,
except for the trivial case... | #EchoLisp | EchoLisp |
(define dim 250)
;; speed up n^5
(define (p5 n) (* n n n n n))
(remember 'p5) ;; memoize
;; build vector of all y^5 - x^5 diffs - length 30877
(define all-y^5-x^5
(for*/vector
[(x (in-range 1 dim)) (y (in-range (1+ x) dim))]
(- (p5 y) (p5 x))))
;; sort to use vector-search
(begin (vector-sort! < all... |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterat... | #Nanoquery | Nanoquery | def factorial(n)
result = 1
for i in range(1, n)
result = result * i
end
return result
end |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #Beads | Beads | beads 1 program 'Even or odd'
calc main_init
loop across:[-10, -5, 10, 5] val:v
log "{v}\todd:{is_odd(v)}\teven:{is_even(v)}" |
http://rosettacode.org/wiki/Euler_method | Euler method | Euler's method numerically approximates solutions of first-order ordinary differential equations (ODEs) with a given initial value. It is an explicit method for solving initial value problems (IVPs), as described in the wikipedia page.
The ODE has to be provided in the following form:
d
y
(
t
)
d
t
=
f... | #Phix | Phix | --
-- demo\rosetta\Euler_method.exw
-- =============================
--
with javascript_semantics
function ivp_euler(atom y, integer f, step, end_t)
sequence res = {}
for t=0 to end_t by step do
if remainder(t,10)==0 then res &= y end if
y += step * call_func(f,{t, y})
end for
return res... |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #GAP | GAP | # Built-in
Binomial(5, 3);
# 10 |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #Go | Go | package main
import "fmt"
import "math/big"
func main() {
fmt.Println(new(big.Int).Binomial(5, 3))
fmt.Println(new(big.Int).Binomial(60, 30))
} |
http://rosettacode.org/wiki/Fibonacci_sequence | Fibonacci sequence | The Fibonacci sequence is a sequence Fn of natural numbers defined recursively:
F0 = 0
F1 = 1
Fn = Fn-1 + Fn-2, if n>1
Task
Write a function to generate the nth Fibonacci number.
Solutions can be iterative or recursive (though recursive solutions are generally considered too slow ... | #XLISP | XLISP | (DEFUN FIBONACCI (N)
(FLOOR (+ (/ (EXPT (/ (+ (SQRT 5) 1) 2) N) (SQRT 5)) 0.5))) |
http://rosettacode.org/wiki/Entropy/Narcissist | Entropy/Narcissist |
Task
Write a computer program that computes and shows its own entropy.
Related Tasks
Fibonacci_word
Entropy
| #Raku | Raku | say log(2) R/ [+] map -> \p { p * -log p }, $_.comb.Bag.values >>/>> +$_
given slurp($*PROGRAM-NAME).comb |
http://rosettacode.org/wiki/Entropy/Narcissist | Entropy/Narcissist |
Task
Write a computer program that computes and shows its own entropy.
Related Tasks
Fibonacci_word
Entropy
| #REXX | REXX | /*REXX program calculates the "information entropy" for ~this~ REXX program. */
numeric digits length( e() ) % 2 - length(.) /*use 1/2 of the decimal digits of E. */
#= 0; @.= 0; $=; $$=; recs= sourceline() /*define some handy─dandy REXX vars. */
do m=1 for recs; $=$||sourceLine(m... |
http://rosettacode.org/wiki/Elliptic_curve_arithmetic | Elliptic curve arithmetic | Elliptic curves are sometimes used in cryptography as a way to perform digital signatures.
The purpose of this task is to implement a simplified (without modular arithmetic) version of the elliptic curve arithmetic which is required by the elliptic curve DSA protocol.
In a nutshell, an elliptic curve is a... | #11l | 11l | T Point
Float x, y
F (x = Float.infinity, y = Float.infinity)
.x = x
.y = y
F.const copy()
R Point(.x, .y)
F.const is_zero()
R .x > 1e20 | .x < -1e20
F neg()
R Point(.x, -.y)
F dbl()
I .is_zero()
R .copy()
I .y == 0
R Point()
... |
http://rosettacode.org/wiki/Enumerations | Enumerations | Task
Create an enumeration of constants with and without explicit values.
| #Erlang | Erlang | type Fruit =
| Apple = 0
| Banana = 1
| Cherry = 2
let basket = [ Fruit.Apple ; Fruit.Banana ; Fruit.Cherry ]
Seq.iter (printfn "%A") basket |
http://rosettacode.org/wiki/Enumerations | Enumerations | Task
Create an enumeration of constants with and without explicit values.
| #F.23 | F# | type Fruit =
| Apple = 0
| Banana = 1
| Cherry = 2
let basket = [ Fruit.Apple ; Fruit.Banana ; Fruit.Cherry ]
Seq.iter (printfn "%A") basket |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #6502_Assembly | 6502 Assembly | EmptyString:
byte 0 |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #68000_Assembly | 68000 Assembly | EmptyString:
DC.B 0
EVEN |
http://rosettacode.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm | Elliptic Curve Digital Signature Algorithm | Elliptic curves.
An elliptic curve E over ℤp (p ≥ 5) is defined by an equation of the form
y^2 = x^3 + ax + b, where a, b ∈ ℤp and the discriminant ≢ 0 (mod p),
together with a special point 𝒪 called the point at infinity.
The set E(ℤp) consists of all points (x, y), with x, y ∈ ℤp,
which satisfy the above defining eq... | #FreeBASIC | FreeBASIC |
'subject: Elliptic curve digital signature algorithm,
' toy version for small modulus N.
'tested : FreeBasic 1.05.0
'rational ec point
type epnt
as longint x, y
end type
'elliptic curve parameters
type curve
as long a, b
as longint N
as epnt G
as longint r
end type
'signature pair
type pair
... |
http://rosettacode.org/wiki/Empty_directory | Empty directory | Starting with a path to some directory, determine whether the directory is empty.
An empty directory contains no files nor subdirectories.
With Unix or Windows systems, every directory contains an entry for “.” and almost every directory contains “..” (except for a root directory); an empty directory contains no other... | #ALGOL_68 | ALGOL 68 | # returns TRUE if the specified directory is empty, FALSE if it doesn't exist or is non-empty #
PROC is empty directory = ( STRING directory )BOOL:
IF NOT file is directory( directory )
THEN
# directory doesn't exist #
FALSE
ELSE
# directory is empty if it contains no files or ... |
http://rosettacode.org/wiki/Empty_directory | Empty directory | Starting with a path to some directory, determine whether the directory is empty.
An empty directory contains no files nor subdirectories.
With Unix or Windows systems, every directory contains an entry for “.” and almost every directory contains “..” (except for a root directory); an empty directory contains no other... | #Arturo | Arturo | emptyDir?: function [folder]-> empty? list folder
print emptyDir? "." |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #360_Assembly | 360 Assembly | BR 14
END |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #6502_Assembly | 6502 Assembly | org $0801 ;start assembling at this address
db $0E,$08,$0A,$00,$9E,$20,$28,$32,$30,$36,$34,$29,$00,$00,$00 ;required init code
rts ;return to basic |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #Factor | Factor | TUPLE: range
{ from read-only } { length read-only } { step read-only } ; |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #Forth | Forth |
256 constant one-hex-dollar
s" Hello world" 2constant hello \ "hello" holds the address and length of an anonymous string.
355 119 2constant ratio-pi \ 2constant can also define ratios (e.g. pi)
3.14159265e fconstant pi
|
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #Fortran | Fortran | real, parameter :: pi = 3.141593 |
http://rosettacode.org/wiki/Enforced_immutability | Enforced immutability | Task
Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.
| #FreeBASIC | FreeBASIC | #define IMMUT1 32767 'constants can be created in the preprocessor
dim as const uinteger IMMUT2 = 2222 'or explicitly declared as constants
|
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #AWK | AWK | #!/usr/bin/awk -f
{
for (i=1; i<= length($0); i++) {
H[substr($0,i,1)]++;
N++;
}
}
END {
for (i in H) {
p = H[i]/N;
E -= p * log(p);
}
print E/log(2);
} |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last ... | #BCPL | BCPL | get "libhdr"
let halve(i) = i>>1
and double(i) = i<<1
and even(i) = (i&1) = 0
let emul(x, y) = emulr(x, y, 0)
and emulr(x, y, ac) =
x=0 -> ac,
emulr(halve(x), double(y), even(x) -> ac, ac + y)
let start() be writef("%N*N", emul(17, 34)) |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #ERRE | ERRE |
PROGRAM EQUILIBRIUM
DIM LISTA[6]
PROCEDURE EQ(LISTA[]->RES$)
LOCAL I%,R,S,E$
FOR I%=0 TO UBOUND(LISTA,1) DO
S+=LISTA[I%]
END FOR
FOR I%=0 TO UBOUND(LISTA,1) DO
IF R=S-R-LISTA[I%] THEN E$+=STR$(I%)+"," END IF
R+=LISTA[I%]
END FOR
RES$=LEFT$(E$,LEN(E$)-1)
END PROCEDURE
BEGIN
... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Euphoria | Euphoria | function equilibrium(sequence s)
integer lower_sum, higher_sum
sequence indices
lower_sum = 0
higher_sum = 0
for i = 1 to length(s) do
higher_sum += s[i]
end for
indices = {}
for i = 1 to length(s) do
higher_sum -= s[i]
if lower_sum = higher_sum then
i... |
http://rosettacode.org/wiki/Environment_variables | Environment variables | Task
Show how to get one of your process's environment variables.
The available variables vary by system; some of the common ones available on Unix include:
PATH
HOME
USER
| #i | i | software {
print(load("$HOME"))
print(load("$USER"))
print(load("$PATH"))
} |
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