diff options
| author | Anthony Martin <ality@pbrane.org> | 2010-10-07 16:10:48 +0200 |
|---|---|---|
| committer | Robert Griesemer <gri@golang.org> | 2010-10-07 16:10:48 +0200 |
| commit | 5781a00e007fb10815e298095fc65b7798278607 (patch) | |
| tree | aa23ee07ba2fe06021c2ab7a32c240350494f273 | |
| parent | 1f6f56390098d0bc922c505dadbc8ee7cc396fa2 (diff) | |
| download | go-5781a00e007fb10815e298095fc65b7798278607.tar.gz go-5781a00e007fb10815e298095fc65b7798278607.zip | |
big: fix panic and round correctly in Rat.FloatString
R=gri, rsc
CC=golang-dev
https://golang.org/cl/2212044
| -rw-r--r-- | src/pkg/big/rat.go | 27 | ||||
| -rw-r--r-- | src/pkg/big/rat_test.go | 5 |
2 files changed, 23 insertions, 9 deletions
diff --git a/src/pkg/big/rat.go b/src/pkg/big/rat.go index 22ae8d2d8b..40c6ef5bd6 100644 --- a/src/pkg/big/rat.go +++ b/src/pkg/big/rat.go @@ -294,25 +294,34 @@ func (z *Rat) FloatString(prec int) string { q, r := nat{}.div(nat{}, z.a.abs, z.b) - s := q.string(10) - if z.a.neg { - s = "-" + s + p := natOne + if prec > 0 { + p = nat{}.expNN(natTen, nat{}.setUint64(uint64(prec)), nil) } - p := nat{}.expNN(natTen, nat{Word(prec)}, nil) r = r.mul(r, p) r, r2 := r.div(nat{}, r, z.b) // see if we need to round up - r2 = r2.mul(r2, natTwo) + r2 = r2.add(r2, r2) if z.b.cmp(r2) <= 0 { r = r.add(r, natOne) + if r.cmp(p) >= 0 { + q = nat{}.add(q, natOne) + r = nat{}.sub(r, p) + } + } + + s := q.string(10) + if z.a.neg { + s = "-" + s } - rs := r.string(10) - leadingZeros := prec - len(rs) - s += "." + strings.Repeat("0", leadingZeros) + rs - s = strings.TrimRight(s, "0") + if prec > 0 { + rs := r.string(10) + leadingZeros := prec - len(rs) + s += "." + strings.Repeat("0", leadingZeros) + rs + } return s } diff --git a/src/pkg/big/rat_test.go b/src/pkg/big/rat_test.go index ccc9cf6056..ff2bb9978b 100644 --- a/src/pkg/big/rat_test.go +++ b/src/pkg/big/rat_test.go @@ -71,6 +71,11 @@ var floatStringTests = []floatStringTest{ floatStringTest{".25", 1, "0.3"}, floatStringTest{"-1/3", 3, "-0.333"}, floatStringTest{"-2/3", 4, "-0.6667"}, + floatStringTest{"0.96", 1, "1.0"}, + floatStringTest{"0.999", 2, "1.00"}, + floatStringTest{"0.9", 0, "1"}, + floatStringTest{".25", -1, "0"}, + floatStringTest{".55", -1, "1"}, } func TestFloatString(t *testing.T) { |