1 files changed, 192 insertions, 0 deletions
diff --git a/libm/float/tanf.c b/libm/float/tanf.c
new file mode 100644
index 000000000..5bbf43075
--- /dev/null
+++ b/libm/float/tanf.c
@@ -0,0 +1,192 @@
+/*							tanf.c
+ *
+ *	Circular tangent
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * float x, y, tanf();
+ *
+ * y = tanf( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns the circular tangent of the radian argument x.
+ *
+ * Range reduction is modulo pi/4.  A polynomial approximation
+ * is employed in the basic interval [0, pi/4].
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Relative error:
+ * arithmetic   domain     # trials      peak         rms
+ *    IEEE     +-4096        100000     3.3e-7      4.5e-8
+ *
+ * ERROR MESSAGES:
+ *
+ *   message         condition          value returned
+ * tanf total loss   x > 2^24              0.0
+ *
+ */
+/*							cotf.c
+ *
+ *	Circular cotangent
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * float x, y, cotf();
+ *
+ * y = cotf( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns the circular cotangent of the radian argument x.
+ * A common routine computes either the tangent or cotangent.
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Relative error:
+ * arithmetic   domain     # trials      peak         rms
+ *    IEEE     +-4096        100000     3.0e-7      4.5e-8
+ *
+ *
+ * ERROR MESSAGES:
+ *
+ *   message         condition          value returned
+ * cot total loss   x > 2^24                0.0
+ * cot singularity  x = 0                  MAXNUMF
+ *
+ */
+
+/*
+Cephes Math Library Release 2.2:  June, 1992
+Copyright 1984, 1987, 1989 by Stephen L. Moshier
+Direct inquiries to 30 Frost Street, Cambridge, MA 02140
+*/
+
+/* Single precision circular tangent
+ * test interval: [-pi/4, +pi/4]
+ * trials: 10000
+ * peak relative error: 8.7e-8
+ * rms relative error: 2.8e-8
+ */
+#include <math.h>
+
+extern float MAXNUMF;
+
+static float DP1 = 0.78515625;
+static float DP2 = 2.4187564849853515625e-4;
+static float DP3 = 3.77489497744594108e-8;
+float FOPI = 1.27323954473516;  /* 4/pi */
+static float lossth = 8192.;
+/*static float T24M1 = 16777215.;*/
+
+
+static float tancotf( float xx, int cotflg )
+{
+float x, y, z, zz;
+long j;
+int sign;
+
+
+/* make argument positive but save the sign */
+if( xx < 0.0 )
+	{
+	x = -xx;
+	sign = -1;
+	}
+else
+	{
+	x = xx;
+	sign = 1;
+	}
+
+if( x > lossth )
+	{
+	if( cotflg )
+		mtherr( "cotf", TLOSS );
+	else
+		mtherr( "tanf", TLOSS );
+	return(0.0);
+	}
+
+/* compute x mod PIO4 */
+j = FOPI * x; /* integer part of x/(PI/4) */
+y = j;
+
+/* map zeros and singularities to origin */
+if( j & 1 )
+	{
+	j += 1;
+	y += 1.0;
+	}
+
+z = ((x - y * DP1) - y * DP2) - y * DP3;
+
+zz = z * z;
+
+if( x > 1.0e-4 )
+	{
+/* 1.7e-8 relative error in [-pi/4, +pi/4] */
+	y =
+	((((( 9.38540185543E-3 * zz
+	+ 3.11992232697E-3) * zz
+	+ 2.44301354525E-2) * zz
+	+ 5.34112807005E-2) * zz
+	+ 1.33387994085E-1) * zz
+	+ 3.33331568548E-1) * zz * z
+	+ z;
+	}
+else
+	{
+	y = z;
+	}
+
+if( j & 2 )
+	{
+	if( cotflg )
+		y = -y;
+	else
+		y = -1.0/y;
+	}
+else
+	{
+	if( cotflg )
+		y = 1.0/y;
+	}
+
+if( sign < 0 )
+	y = -y;
+
+return( y );
+}
+
+
+float tanf( float x )
+{
+
+return( tancotf(x,0) );
+}
+
+float cotf( float x )
+{
+
+if( x == 0.0 )
+	{
+	mtherr( "cotf", SING );
+	return( MAXNUMF );
+	}
+return( tancotf(x,1) );
+}
+