| // Copyright 2009 The Go Authors. All rights reserved. | |
| // Use of this source code is governed by a BSD-style | |
| // license that can be found in the LICENSE file. | |
| //go:build ignore | |
| package main | |
| import ( | |
| big "." | |
| "fmt" | |
| "runtime" | |
| ) | |
| var ( | |
| tmp1 = big.NewInt(0) | |
| tmp2 = big.NewInt(0) | |
| numer = big.NewInt(1) | |
| accum = big.NewInt(0) | |
| denom = big.NewInt(1) | |
| ten = big.NewInt(10) | |
| ) | |
| func extractDigit() int64 { | |
| if big.CmpInt(numer, accum) > 0 { | |
| return -1 | |
| } | |
| tmp1.Lsh(numer, 1).Add(tmp1, numer).Add(tmp1, accum) | |
| big.DivModInt(tmp1, tmp2, tmp1, denom) | |
| tmp2.Add(tmp2, numer) | |
| if big.CmpInt(tmp2, denom) >= 0 { | |
| return -1 | |
| } | |
| return tmp1.Int64() | |
| } | |
| func nextTerm(k int64) { | |
| y2 := k*2 + 1 | |
| accum.Add(accum, tmp1.Lsh(numer, 1)) | |
| accum.Mul(accum, tmp1.SetInt64(y2)) | |
| numer.Mul(numer, tmp1.SetInt64(k)) | |
| denom.Mul(denom, tmp1.SetInt64(y2)) | |
| } | |
| func eliminateDigit(d int64) { | |
| accum.Sub(accum, tmp1.Mul(denom, tmp1.SetInt64(d))) | |
| accum.Mul(accum, ten) | |
| numer.Mul(numer, ten) | |
| } | |
| func main() { | |
| i := 0 | |
| k := int64(0) | |
| for { | |
| d := int64(-1) | |
| for d < 0 { | |
| k++ | |
| nextTerm(k) | |
| d = extractDigit() | |
| } | |
| eliminateDigit(d) | |
| fmt.Printf("%c", d+'0') | |
| if i++; i%50 == 0 { | |
| fmt.Printf("\n") | |
| if i >= 1000 { | |
| break | |
| } | |
| } | |
| } | |
| fmt.Printf("\n%d calls; bit sizes: %d %d %d\n", runtime.NumCgoCall(), numer.Len(), accum.Len(), denom.Len()) | |
| } | |