_WMRTLINK double _IF_datan( double x )
/************************************/
{
char add_piby2;
char add_piby6;
int sgnx;
double tmp;
#if defined(_M_IX86)
if( _RWD_real87 )
return( _atan87(x) );
#endif
add_piby2 = FALSE;
add_piby6 = FALSE;
sgnx = __sgn( x );
x = fabs( x );
if( x == 1.0 ) { /* 06-dec-88 */
x = PIby4;
} else if( x > (1.0 / DBL_MIN) ) {
x = PIby2;
} else if( x < (DBL_MIN / MIN_POLY_CONST) ) {
x = DBL_MIN;
} else {
if( x > 1.0 ) {
x = PDIV( 1.0, x );
add_piby2 = TRUE;
}
if( x > tan15 ) {
tmp = sqrt3m1 * x - 0.5;
tmp -= 0.5;
x = PDIV( (tmp + x), (x + sqrt3) );
// x = (x * sqrt3 - 1.0) / (x + sqrt3);
add_piby6 = TRUE;
}
x = _OddPoly( x, AtanPoly, 8 );
if( add_piby6 ) {
x += PIby6;
}
if( add_piby2 ) {
x = PIby2 - x;
}
}
if( sgnx < 0 ) {
x = -x;
}
return( x );
}
_WMRTLINK double _IF_datan2( double y, double x )
/***********************************************/
{
int sgnx; /* sgn(x) */
int sgny; /* sgn(y) */
int sgnz; /* sgn(z) */
sgny = __sgn( y );
sgnx = __sgn( x );
if( sgny == 0 ) { /* case 1 */
if( sgnx == 0 ) {
x = __math2err( FUNC_ATAN2 | M_DOMAIN | V_ZERO, &y, &x );
} else if( sgnx < 0 ) {
x = Pi;
} else {
x = 0.0;
}
} else if( sgnx == 0 ) { /* case 2 */
if( sgny < 0 ) {
x = -Piby2;
} else {
x = Piby2;
}
} else {
int exp_x;
int exp_y;
int diff_exp_y_x;
frexp( y, &exp_y );
frexp( x, &exp_x );
diff_exp_y_x = exp_y - exp_x;
if( diff_exp_y_x > DBL_MAX_EXP ) {
if( sgnx == sgny ) {
x = +DBL_MAX;
} else {
x = -DBL_MAX;
}
} else if( diff_exp_y_x < DBL_MIN_EXP ) {
if( sgnx == sgny ) {
x = +DBL_MIN;
} else {
x = -DBL_MIN;
}
} else {
x = PDIV( y, x );
}
x = atan( x );
sgnz = __sgn( x );
if( sgny >= 0 ) {
if( sgnz < 0 ) {
x += Pi;
}
} else {
if( sgnz > 0 ) {
x -= Pi;
}
}
}
return( x );
}
_WMRTLINK double _IF_dexp( double x )
/***********************************/
{
int sgnx;
int exp;
int exp2;
const double *poly;
double ipart;
double a;
double b;
double ee;
if( fabs( x ) < 4.445e-16 ) { /* if argument is too small */
x = 1.0;
} else if( fabs( x ) > 709.782712893384 ) {/* if argument is too large */
if( x < 0.0 ) {
/* FPStatus = FPS_UNDERFLOW; - - underflow */
x = 0.0; /* - - set result to 0 */
} else {
x = __math1err( FP_FUNC_EXP | M_OVERFLOW | V_HUGEVAL, &x );
}
#if defined(_M_IX86)
} else if( _RWD_real87 ) {
x = _exp87( x );
#endif
} else {
x *= log2e;
sgnx = __sgn( x );
x = modf( fabs( x ), &ipart );
exp = ipart;
if( sgnx < 0 ) {
exp = -exp;
if( x != 0.0 ) {
--exp;
x = 1.0 - x;
}
}
exp2 = 0;
if( x != 0.0 ) {
x = modf( ldexp( x, 4 ), &ipart );
if( x != 0.0 ) {
x = ldexp( x, -4 );
}
exp2 = ipart;
}
ee = x * x;
a = ee + const0;
b = (ee * const1 + const2) * x;
x = (a + b) / (a - b);
poly = ExpConsts;
while( exp2 != 0 ) {
if( exp2 & 1 ) {
x *= *poly;
}
++poly;
exp2 = exp2 >> 1;
}
x = ldexp( x, exp );
}
return( x );
}
