3 files changed, 32 insertions, 0 deletions
diff --git a/src/pkg/math/cmplx/cmath_test.go b/src/pkg/math/cmplx/cmath_test.go
index 610ca8ceb..f285646af 100644
--- a/src/pkg/math/cmplx/cmath_test.go
+++ b/src/pkg/math/cmplx/cmath_test.go
@@ -656,6 +656,19 @@ func TestPolar(t *testing.T) {
 	}
 }
 func TestPow(t *testing.T) {
+	// Special cases for Pow(0, c).
+	var zero = complex(0, 0)
+	zeroPowers := [][2]complex128{
+		{0, 1 + 0i},
+		{1.5, 0 + 0i},
+		{-1.5, complex(math.Inf(0), 0)},
+		{-1.5 + 1.5i, Inf()},
+	}
+	for _, zp := range zeroPowers {
+		if f := Pow(zero, zp[0]); f != zp[1] {
+			t.Errorf("Pow(%g, %g) = %g, want %g", zero, zp[0], f, zp[1])
+		}
+	}
 	var a = complex(3.0, 3.0)
 	for i := 0; i < len(vc); i++ {
 		if f := Pow(a, vc[i]); !cSoclose(pow[i], f, 4e-15) {
diff --git a/src/pkg/math/cmplx/pow.go b/src/pkg/math/cmplx/pow.go
index 4dbc58398..1630b879b 100644
--- a/src/pkg/math/cmplx/pow.go
+++ b/src/pkg/math/cmplx/pow.go
@@ -43,7 +43,25 @@ import "math"
 //    IEEE      -10,+10     30000       9.4e-15     1.5e-15
 
 // Pow returns x**y, the base-x exponential of y.
+// For generalized compatibility with math.Pow:
+//	Pow(0, ±0) returns 1+0i
+//	Pow(0, c) for real(c)<0 returns Inf+0i if imag(c) is zero, otherwise Inf+Inf i.
 func Pow(x, y complex128) complex128 {
+	if x == 0 { // Guaranteed also true for x == -0.
+		r, i := real(y), imag(y)
+		switch {
+		case r == 0:
+			return 1
+		case r < 0:
+			if i == 0 {
+				return complex(math.Inf(1), 0)
+			}
+			return Inf()
+		case r > 0:
+			return 0
+		}
+		panic("not reached")
+	}
 	modulus := Abs(x)
 	if modulus == 0 {
 		return complex(0, 0)
diff --git a/src/pkg/math/cmplx/sqrt.go b/src/pkg/math/cmplx/sqrt.go
index 179b5396a..4ef6807ad 100644
--- a/src/pkg/math/cmplx/sqrt.go
+++ b/src/pkg/math/cmplx/sqrt.go
@@ -54,6 +54,7 @@ import "math"
 //    IEEE      -10,+10   1,000,000     2.9e-16     6.1e-17
 
 // Sqrt returns the square root of x.
+// The result r is chosen so that real(r) ≥ 0 and imag(r) has the same sign as imag(x).
 func Sqrt(x complex128) complex128 {
 	if imag(x) == 0 {
 		if real(x) == 0 {