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authorEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
committerEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
commit1077fa4d772832f77a677ce7fb7c2d513b959e3f (patch)
tree579bee13fb0b58d2800206366ec2caecbb15f3fc /libm/double/tandg.c
parent22358dd7ce7bb49792204b698f01a6f69b9c8e08 (diff)
uClibc now has a math library. muahahahaha!
-Erik
Diffstat (limited to 'libm/double/tandg.c')
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diff --git a/libm/double/tandg.c b/libm/double/tandg.c
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+/* tandg.c
+ *
+ * Circular tangent of argument in degrees
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double x, y, tandg();
+ *
+ * y = tandg( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns the circular tangent of the argument x in degrees.
+ *
+ * Range reduction is modulo pi/4. A rational function
+ * x + x**3 P(x**2)/Q(x**2)
+ * is employed in the basic interval [0, pi/4].
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ * Relative error:
+ * arithmetic domain # trials peak rms
+ * DEC 0,10 8000 3.4e-17 1.2e-17
+ * IEEE 0,10 30000 3.2e-16 8.4e-17
+ *
+ * ERROR MESSAGES:
+ *
+ * message condition value returned
+ * tandg total loss x > 8.0e14 (DEC) 0.0
+ * x > 1.0e14 (IEEE)
+ * tandg singularity x = 180 k + 90 MAXNUM
+ */
+ /* cotdg.c
+ *
+ * Circular cotangent of argument in degrees
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double x, y, cotdg();
+ *
+ * y = cotdg( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns the circular cotangent of the argument x in degrees.
+ *
+ * Range reduction is modulo pi/4. A rational function
+ * x + x**3 P(x**2)/Q(x**2)
+ * is employed in the basic interval [0, pi/4].
+ *
+ *
+ * ERROR MESSAGES:
+ *
+ * message condition value returned
+ * cotdg total loss x > 8.0e14 (DEC) 0.0
+ * x > 1.0e14 (IEEE)
+ * cotdg singularity x = 180 k MAXNUM
+ */
+
+/*
+Cephes Math Library Release 2.8: June, 2000
+Copyright 1984, 1987, 2000 by Stephen L. Moshier
+*/
+
+#include <math.h>
+
+#ifdef UNK
+static double P[] = {
+-1.30936939181383777646E4,
+ 1.15351664838587416140E6,
+-1.79565251976484877988E7
+};
+static double Q[] = {
+/* 1.00000000000000000000E0,*/
+ 1.36812963470692954678E4,
+-1.32089234440210967447E6,
+ 2.50083801823357915839E7,
+-5.38695755929454629881E7
+};
+static double PI180 = 1.74532925199432957692E-2;
+static double lossth = 1.0e14;
+#endif
+
+#ifdef DEC
+static unsigned short P[] = {
+0143514,0113306,0111171,0174674,
+0045214,0147545,0027744,0167346,
+0146210,0177526,0114514,0105660
+};
+static unsigned short Q[] = {
+/*0040200,0000000,0000000,0000000,*/
+0043525,0142457,0072633,0025617,
+0145241,0036742,0140525,0162256,
+0046276,0146176,0013526,0143573,
+0146515,0077401,0162762,0150607
+};
+static unsigned short P1[] = {0036616,0175065,0011224,0164711};
+#define PI180 *(double *)P1
+static double lossth = 8.0e14;
+#endif
+
+#ifdef IBMPC
+static unsigned short P[] = {
+0x3f38,0xd24f,0x92d8,0xc0c9,
+0x9ddd,0xa5fc,0x99ec,0x4131,
+0x9176,0xd329,0x1fea,0xc171
+};
+static unsigned short Q[] = {
+/*0x0000,0x0000,0x0000,0x3ff0,*/
+0x6572,0xeeb3,0xb8a5,0x40ca,
+0xbc96,0x582a,0x27bc,0xc134,
+0xd8ef,0xc2ea,0xd98f,0x4177,
+0x5a31,0x3cbe,0xafe0,0xc189
+};
+static unsigned short P1[] = {0x9d39,0xa252,0xdf46,0x3f91};
+#define PI180 *(double *)P1
+static double lossth = 1.0e14;
+#endif
+
+#ifdef MIEEE
+static unsigned short P[] = {
+0xc0c9,0x92d8,0xd24f,0x3f38,
+0x4131,0x99ec,0xa5fc,0x9ddd,
+0xc171,0x1fea,0xd329,0x9176
+};
+static unsigned short Q[] = {
+0x40ca,0xb8a5,0xeeb3,0x6572,
+0xc134,0x27bc,0x582a,0xbc96,
+0x4177,0xd98f,0xc2ea,0xd8ef,
+0xc189,0xafe0,0x3cbe,0x5a31
+};
+static unsigned short P1[] = {
+0x3f91,0xdf46,0xa252,0x9d39
+};
+#define PI180 *(double *)P1
+static double lossth = 1.0e14;
+#endif
+
+#ifdef ANSIPROT
+extern double polevl ( double, void *, int );
+extern double p1evl ( double, void *, int );
+extern double floor ( double );
+extern double ldexp ( double, int );
+static double tancot( double, int );
+#else
+double polevl(), p1evl(), floor(), ldexp();
+static double tancot();
+#endif
+extern double MAXNUM;
+extern double PIO4;
+
+
+double tandg(x)
+double x;
+{
+
+return( tancot(x,0) );
+}
+
+
+double cotdg(x)
+double x;
+{
+
+return( tancot(x,1) );
+}
+
+
+static double tancot( xx, cotflg )
+double xx;
+int cotflg;
+{
+double x, y, z, zz;
+int j, sign;
+
+/* make argument positive but save the sign */
+if( xx < 0 )
+ {
+ x = -xx;
+ sign = -1;
+ }
+else
+ {
+ x = xx;
+ sign = 1;
+ }
+
+if( x > lossth )
+ {
+ mtherr( "tandg", TLOSS );
+ return(0.0);
+ }
+
+/* compute x mod PIO4 */
+y = floor( x/45.0 );
+
+/* strip high bits of integer part */
+z = ldexp( y, -3 );
+z = floor(z); /* integer part of y/8 */
+z = y - ldexp( z, 3 ); /* y - 16 * (y/16) */
+
+/* integer and fractional part modulo one octant */
+j = z;
+
+/* map zeros and singularities to origin */
+if( j & 1 )
+ {
+ j += 1;
+ y += 1.0;
+ }
+
+z = x - y * 45.0;
+z *= PI180;
+
+zz = z * z;
+
+if( zz > 1.0e-14 )
+ y = z + z * (zz * polevl( zz, P, 2 )/p1evl(zz, Q, 4));
+else
+ y = z;
+
+if( j & 2 )
+ {
+ if( cotflg )
+ y = -y;
+ else
+ {
+ if( y != 0.0 )
+ {
+ y = -1.0/y;
+ }
+ else
+ {
+ mtherr( "tandg", SING );
+ y = MAXNUM;
+ }
+ }
+ }
+else
+ {
+ if( cotflg )
+ {
+ if( y != 0.0 )
+ y = 1.0/y;
+ else
+ {
+ mtherr( "cotdg", SING );
+ y = MAXNUM;
+ }
+ }
+ }
+
+if( sign < 0 )
+ y = -y;
+
+return( y );
+}