84 lines
1.3 KiB
Go
84 lines
1.3 KiB
Go
// Copyright (c) jnml. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build ignore
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// Factor Finder - searches for Mersenne number factors of one specific special
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// form.
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package main
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import (
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"flag"
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"fmt"
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"math/big"
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"runtime"
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"time"
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"github.com/cznic/mathutil"
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)
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const (
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pp = 1
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pp2 = 10
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)
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var (
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_1 = big.NewInt(1)
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_2 = big.NewInt(2)
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)
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func main() {
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runtime.GOMAXPROCS(2)
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oClass := flag.Uint64("c", 2, `factor "class" number`)
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oDuration := flag.Duration("d", time.Second, "duration to spend on one class")
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flag.Parse()
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class := *oClass
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for class&1 != 0 {
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class >>= 1
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}
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class = mathutil.MaxUint64(class, 2)
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for {
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c := time.After(*oDuration)
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factor := big.NewInt(0)
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factor.SetUint64(class)
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exp := big.NewInt(0)
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oneClass:
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for {
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select {
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case <-c:
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break oneClass
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default:
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}
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exp.Set(factor)
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factor.Lsh(factor, 1)
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factor.Add(factor, _1)
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if !factor.ProbablyPrime(pp) {
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continue
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}
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if !exp.ProbablyPrime(pp) {
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continue
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}
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if mathutil.ModPowBigInt(_2, exp, factor).Cmp(_1) != 0 {
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continue
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}
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if !factor.ProbablyPrime(pp2) {
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continue
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}
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if !exp.ProbablyPrime(pp2) {
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continue
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}
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fmt.Printf("%d: %s | M%s (%d bits)\n", class, factor, exp, factor.BitLen())
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}
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class += 2
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}
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}
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