math/big: add more Float.Float64 conversion tests
- structure the Float64 conversion tests the same way as for Float32
- add additional test cases, including one that exposes a current issue
(currently disabled, same issue as was fixed for Float32)
The Float64 fix will be in a subsequent change for easier reviewing.
Change-Id: I95dc9e8d1f6b6073a98c7bc2289e6d3248fc3420
Reviewed-on: https://go-review.googlesource.com/10351
Reviewed-by: Alan Donovan <adonovan@google.com>
diff --git a/src/math/big/float_test.go b/src/math/big/float_test.go
index 4da145b..92eec71 100644
--- a/src/math/big/float_test.go
+++ b/src/math/big/float_test.go
@@ -209,6 +209,12 @@
}
+func alike64(x, y float64) bool {
+ // we can ignore NaNs
+ return x == y && math.Signbit(x) == math.Signbit(y)
+
+}
+
func TestFloatMantExp(t *testing.T) {
for _, test := range []struct {
x string
@@ -908,35 +914,37 @@
out float64
acc Accuracy
}{
- {"-Inf", math.Inf(-1), Exact},
- {"-0x1.fffffffffffff8p2147483646", -math.Inf(+1), Below}, // overflow in rounding
- {"-1e10000", math.Inf(-1), Below}, // overflow
- {"-0x1p1024", math.Inf(-1), Below}, // overflow
- {"-0x1.fffffffffffff8p1023", -math.Inf(+1), Below}, // overflow
- {"-0x1.fffffffffffff4p1023", -math.MaxFloat64, Above},
- {"-0x1.fffffffffffff0p1023", -math.MaxFloat64, Exact},
- {"-12345.000000000000000000001", -12345, Above},
- {"-12345.0", -12345, Exact},
- {"-1.000000000000000000001", -1, Above},
- {"-1", -1, Exact},
- {"-0x0.0000000000001p-1022", -math.SmallestNonzeroFloat64, Exact},
- {"-0x0.0000000000001p-1023", -0, Above}, // underflow
- {"-1e-1000", -0, Above}, // underflow
{"0", 0, Exact},
- {"1e-1000", 0, Below}, // underflow
- {"0x0.0000000000001p-1023", 0, Below}, // underflow
- {"0x0.0000000000001p-1022", math.SmallestNonzeroFloat64, Exact},
+
+ // underflow
+ {"1e-1000", 0, Below},
+ {"0x0.0000000000001p-1023", 0, Below},
+ {"0x0.00000000000008p-1022", 0, Below},
+
+ // denormals
+ // TODO(gri) enable once Float64 is fixed
+ // {"0x0.0000000000000cp-1022", math.SmallestNonzeroFloat64, Above}, // rounded up to smallest denormal
+ {"0x0.0000000000001p-1022", math.SmallestNonzeroFloat64, Exact}, // smallest denormal
+ {"0x.8p-1073", math.SmallestNonzeroFloat64, Exact},
+ {"1p-1074", math.SmallestNonzeroFloat64, Exact},
+ {"0x.fffffffffffffp-1022", math.Float64frombits(0x000fffffffffffff), Exact}, // largest denormal
+
+ // normals
+ {"0x.fffffffffffff8p-1022", math.Float64frombits(0x0010000000000000), Above}, // rounded up to smallest normal
+ {"1p-1022", math.Float64frombits(0x0010000000000000), Exact}, // smallest normal
{"1", 1, Exact},
{"1.000000000000000000001", 1, Below},
{"12345.0", 12345, Exact},
{"12345.000000000000000000001", 12345, Below},
{"0x1.fffffffffffff0p1023", math.MaxFloat64, Exact},
{"0x1.fffffffffffff4p1023", math.MaxFloat64, Below},
- {"0x1.fffffffffffff8p1023", math.Inf(+1), Above}, // overflow
- {"0x1p1024", math.Inf(+1), Above}, // overflow
- {"1e10000", math.Inf(+1), Above}, // overflow
+
+ // overflow
+ {"0x1.fffffffffffff8p1023", math.Inf(+1), Above},
+ {"0x1p1024", math.Inf(+1), Above},
+ {"1e10000", math.Inf(+1), Above},
{"0x1.fffffffffffff8p2147483646", math.Inf(+1), Above}, // overflow in rounding
- {"+Inf", math.Inf(+1), Exact},
+ {"Inf", math.Inf(+1), Exact},
// selected denormalized values that were handled incorrectly in the past
{"0x.fffffffffffffp-1022", smallestNormalFloat64 - math.SmallestNonzeroFloat64, Exact},
@@ -947,22 +955,32 @@
// http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
{"2.2250738585072012e-308", 2.2250738585072014e-308, Above},
} {
- // conversion should match strconv where syntax is agreeable
- if f, err := strconv.ParseFloat(test.x, 64); err == nil && f != test.out {
- t.Errorf("%s: got %g; want %g (incorrect test data)", test.x, f, test.out)
- }
+ for i := 0; i < 2; i++ {
+ // test both signs
+ tx, tout, tacc := test.x, test.out, test.acc
+ if i != 0 {
+ tx = "-" + tx
+ tout = -tout
+ tacc = -tacc
+ }
- x := makeFloat(test.x)
- out, acc := x.Float64()
- if out != test.out || acc != test.acc {
- t.Errorf("%s: got %g (%#x, %s); want %g (%#x, %s)", test.x, out, math.Float64bits(out), acc, test.out, math.Float64bits(test.out), test.acc)
- }
+ // conversion should match strconv where syntax is agreeable
+ if f, err := strconv.ParseFloat(tx, 64); err == nil && !alike64(f, tout) {
+ t.Errorf("%s: got %g; want %g (incorrect test data)", tx, f, tout)
+ }
- // test that x.SetFloat64(f).Float64() == f
- var x2 Float
- out2, acc2 := x2.SetFloat64(out).Float64()
- if out2 != out || acc2 != Exact {
- t.Errorf("idempotency test: got %g (%s); want %g (Exact)", out2, acc2, out)
+ x := makeFloat(tx)
+ out, acc := x.Float64()
+ if !alike64(out, tout) || acc != tacc {
+ t.Errorf("%s: got %g (%#x, %s); want %g (%#x, %s)", tx, out, math.Float64bits(out), acc, test.out, math.Float64bits(test.out), tacc)
+ }
+
+ // test that x.SetFloat64(f).Float64() == f
+ var x2 Float
+ out2, acc2 := x2.SetFloat64(out).Float64()
+ if !alike64(out2, out) || acc2 != Exact {
+ t.Errorf("idempotency test: got %g (%s); want %g (Exact)", out2, acc2, out)
+ }
}
}
}
