From: Robert Griesemer <gri@golang.org>
Date: Sun, 15 Feb 2015 05:29:37 +0000 (-0800)
Subject: math/big: implement fast path in Float.SetRat if argument is integer
X-Git-Tag: go1.5beta1~1984
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=61c9c3ddc4f972cef41aad8e78bdc1746d5c5a4a;p=gostls13.git

math/big: implement fast path in Float.SetRat if argument is integer

Change-Id: Ib82500e198b86e9fade278c7eea7a4b0c6b0b2e1
Reviewed-on: https://go-review.googlesource.com/4921
Reviewed-by: Rob Pike <r@golang.org>
---

diff --git a/src/math/big/float.go b/src/math/big/float.go
index 739d30f7ad..877379c901 100644
--- a/src/math/big/float.go
+++ b/src/math/big/float.go
@@ -582,7 +582,9 @@ func (z *Float) SetInt(x *Int) *Float {
 // If z's precision is 0, it is changed to the largest of a.BitLen(),
 // b.BitLen(), or 64; with x = a/b.
 func (z *Float) SetRat(x *Rat) *Float {
-	// TODO(gri) can be more efficient if x is an integer
+	if x.IsInt() {
+		return z.SetInt(x.Num())
+	}
 	var a, b Float
 	a.SetInt(x.Num())
 	b.SetInt(x.Denom())