| // 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()) |
| } |
