1 files changed, 66 insertions, 0 deletions
diff --git a/src/pkg/math/sqrt.go b/src/pkg/math/sqrt.go
new file mode 100644
index 000000000..79384f648
--- /dev/null
+++ b/src/pkg/math/sqrt.go
@@ -0,0 +1,66 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package math
+
+import "math"
+
+/*
+ *	sqrt returns the square root of its floating
+ *	point argument. Newton's method.
+ *
+ *	calls frexp
+ */
+
+// Sqrt returns the square root of x.
+//
+// Special cases are:
+//	Sqrt(+Inf) = +Inf
+//	Sqrt(0) = 0
+//	Sqrt(x < 0) = NaN
+func Sqrt(x float64) float64 {
+	if IsInf(x, 1) {
+		return x;
+	}
+
+	if x <= 0 {
+		if x < 0 {
+			return NaN();
+		}
+		return 0;
+	}
+
+	y, exp := Frexp(x);
+	for y < 0.5 {
+		y = y*2;
+		exp = exp-1;
+	}
+
+	if exp&1 != 0 {
+		y = y*2;
+		exp = exp-1;
+	}
+	temp := 0.5 * (1+y);
+
+	for exp > 60 {
+		temp = temp * float64(1<<30);
+		exp = exp - 60;
+	}
+	for exp < -60 {
+		temp = temp / float64(1<<30);
+		exp = exp + 60;
+	}
+	if exp >= 0 {
+		exp = 1 << uint(exp/2);
+		temp = temp * float64(exp);
+	} else {
+		exp = 1 << uint(-exp/2);
+		temp = temp / float64(exp);
+	}
+
+	for i:=0; i<=4; i++ {
+		temp = 0.5*(temp + x/temp);
+	}
+	return temp;
+}