1 files changed, 65 insertions, 0 deletions
diff --git a/src/pkg/math/sin.go b/src/pkg/math/sin.go
new file mode 100644
index 000000000..8a2edd7e5
--- /dev/null
+++ b/src/pkg/math/sin.go
@@ -0,0 +1,65 @@
+// 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
+
+/*
+	Floating-point sine and cosine.
+
+	Coefficients are #5077 from Hart & Cheney. (18.80D)
+*/
+
+func sinus(x float64, quad int) float64 {
+	const (
+		P0 = .1357884097877375669092680e8
+		P1 = -.4942908100902844161158627e7
+		P2 = .4401030535375266501944918e6
+		P3 = -.1384727249982452873054457e5
+		P4 = .1459688406665768722226959e3
+		Q0 = .8644558652922534429915149e7
+		Q1 = .4081792252343299749395779e6
+		Q2 = .9463096101538208180571257e4
+		Q3 = .1326534908786136358911494e3
+	)
+	if x < 0 {
+		x = -x
+		quad = quad + 2
+	}
+	x = x * (2 / Pi) /* underflow? */
+	var y float64
+	if x > 32764 {
+		var e float64
+		e, y = Modf(x)
+		e = e + float64(quad)
+		f, _ := Modf(0.25 * e)
+		quad = int(e - 4*f)
+	} else {
+		k := int32(x)
+		y = x - float64(k)
+		quad = (quad + int(k)) & 3
+	}
+
+	if quad&1 != 0 {
+		y = 1 - y
+	}
+	if quad > 1 {
+		y = -y
+	}
+
+	yy := y * y
+	temp1 := ((((P4*yy+P3)*yy+P2)*yy+P1)*yy + P0) * y
+	temp2 := ((((yy+Q3)*yy+Q2)*yy+Q1)*yy + Q0)
+	return temp1 / temp2
+}
+
+// Cos returns the cosine of x.
+func Cos(x float64) float64 {
+	if x < 0 {
+		x = -x
+	}
+	return sinus(x, 1)
+}
+
+// Sin returns the sine of x.
+func Sin(x float64) float64 { return sinus(x, 0) }