math/big: add "smoke test" for big.Float division
Change-Id: Ica419a1215ca33dc1cff1e9e4137f204591e3cee
Reviewed-on: https://go-review.googlesource.com/3942
Reviewed-by: Alan Donovan <adonovan@google.com>
diff --git a/src/math/big/float_test.go b/src/math/big/float_test.go
index ec67a6d..e37d2ed 100644
--- a/src/math/big/float_test.go
+++ b/src/math/big/float_test.go
@@ -521,6 +521,47 @@
}
}
+// TestFloatQuoSmoke tests all divisions x/y for values x, y in the range [-n, +n];
+// it serves as a smoke test for basic correctness of division.
+func TestFloatQuoSmoke(t *testing.T) {
+ n := 1000
+ if testing.Short() {
+ n = 10
+ }
+
+ const dprec = 3 // max. precision variation
+ const prec = 10 + dprec // enough bits to hold n precisely
+ for x := -n; x <= n; x++ {
+ for y := -n; y < n; y++ {
+ if y == 0 {
+ continue
+ }
+
+ a := float64(x)
+ b := float64(y)
+ c := a / b
+
+ // vary operand precision (only ok as long as a, b can be represented correctly)
+ for ad := -dprec; ad <= dprec; ad++ {
+ for bd := -dprec; bd <= dprec; bd++ {
+ A := NewFloat(a, uint(prec+ad), 0)
+ B := NewFloat(b, uint(prec+bd), 0)
+ C := NewFloat(0, 53, 0).Quo(A, B) // C has float64 mantissa width
+
+ cc, acc := C.Float64()
+ if cc != c {
+ t.Errorf("%g/%g = %s; want %.5g\n", a, b, C.Format('g', 5), c)
+ continue
+ }
+ if acc != Exact {
+ t.Errorf("%g/%g got %s result; want exact result", a, b, acc)
+ }
+ }
+ }
+ }
+ }
+}
+
// normBits returns the normalized bits for x: It
// removes multiple equal entries by treating them
// as an addition (e.g., []int{5, 5} => []int{6}),
