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..9fc69606c
--- /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
+
+import "math"
+
+func sinus(x float64, quad int) float64 {
+	// Coefficients are #3370 from Hart & Cheney (18.80D).
+	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);
+		temp1, 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);
+}