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Diffstat (limited to 'libm/float/tandgf.c')
| -rw-r--r-- | libm/float/tandgf.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/libm/float/tandgf.c b/libm/float/tandgf.c new file mode 100644 index 000000000..dc55ad5e4 --- /dev/null +++ b/libm/float/tandgf.c @@ -0,0 +1,206 @@ +/* tandgf.c + * + * Circular tangent of angle in degrees + * + * + * + * SYNOPSIS: + * + * float x, y, tandgf(); + * + * y = tandgf( x ); + * + * + * + * DESCRIPTION: + * + * Returns the circular tangent of the radian argument x. + * + * Range reduction is into intervals of 45 degrees. + * + * + * + * + * ACCURACY: + * + * Relative error: + * arithmetic domain # trials peak rms + * IEEE +-2^24 50000 2.4e-7 4.8e-8 + * + * ERROR MESSAGES: + * + * message condition value returned + * tanf total loss x > 2^24 0.0 + * + */ + /* cotdgf.c + * + * Circular cotangent of angle in degrees + * + * + * + * SYNOPSIS: + * + * float x, y, cotdgf(); + * + * y = cotdgf( x ); + * + * + * + * DESCRIPTION: + * + * Range reduction is into intervals of 45 degrees. + * A common routine computes either the tangent or cotangent. + * + * + * + * ACCURACY: + * + * Relative error: + * arithmetic domain # trials peak rms + * IEEE +-2^24 50000 2.4e-7 4.8e-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, 1992 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 T24M1 = 16777215.; +static float PI180 = 0.0174532925199432957692; /* pi/180 */ + +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 > T24M1 ) + { + if( cotflg ) + mtherr( "cotdgf", TLOSS ); + else + mtherr( "tandgf", TLOSS ); + return(0.0); + } + +/* compute x mod PIO4 */ +j = 0.022222222222222222222 * x; /* integer part of x/45 */ +y = j; + +/* map zeros and singularities to origin */ +if( j & 1 ) + { + j += 1; + y += 1.0; + } + +z = x - y * 45.0; +z *= PI180; /* multiply by pi/180 to convert to radians */ + +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 + { + if( y != 0.0 ) + { + y = -1.0/y; + } + else + { + mtherr( "tandgf", SING ); + y = MAXNUMF; + } + } + } +else + { + if( cotflg ) + { + if( y != 0.0 ) + y = 1.0/y; + else + { + mtherr( "cotdgf", SING ); + y = MAXNUMF; + } + } + } + +if( sign < 0 ) + y = -y; + +return( y ); +} + + +float tandgf( float x ) +{ + +return( tancotf(x,0) ); +} + +float cotdgf( float x ) +{ + +if( x == 0.0 ) + { + mtherr( "cotdgf", SING ); + return( MAXNUMF ); + } +return( tancotf(x,1) ); +} + |