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https://github.com/golang/go
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40 lines
811 B
Go
40 lines
811 B
Go
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// Copyright 2009 The Go Authors. 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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package eval
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import (
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"bignum";
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)
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// TODO(austin): Maybe add to bignum in more general form
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func ratToString(rat *bignum.Rational) string {
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n, dnat := rat.Value();
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d := bignum.MakeInt(false, dnat);
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w, frac := n.QuoRem(d);
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out := w.String();
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if frac.IsZero() {
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return out;
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}
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r := frac.Abs();
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r = r.Mul(bignum.Nat(1e6));
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dec, tail := r.DivMod(dnat);
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// Round last digit
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if tail.Cmp(dnat.Div(bignum.Nat(2))) >= 0 {
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dec = dec.Add(bignum.Nat(1));
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}
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// Strip zeros
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ten := bignum.Nat(10);
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for !dec.IsZero() {
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dec2, r2 := dec.DivMod(ten);
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if !r2.IsZero() {
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break;
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}
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dec = dec2;
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}
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out += "." + dec.String();
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return out;
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}
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