/*
* x
* arcsin(x) = arctan(---------------)
* sqrt(1 - x^2)
*/
struct fpn *
fpu_asin(struct fpemu *fe)
{
struct fpn x;
struct fpn *r;
if (ISNAN(&fe->fe_f2))
return &fe->fe_f2;
if (ISZERO(&fe->fe_f2))
return &fe->fe_f2;
if (ISINF(&fe->fe_f2))
return fpu_newnan(fe);
CPYFPN(&x, &fe->fe_f2);
/* x^2 */
CPYFPN(&fe->fe_f1, &fe->fe_f2);
r = fpu_mul(fe);
/* 1 - x^2 */
CPYFPN(&fe->fe_f2, r);
fe->fe_f2.fp_sign = 1;
fpu_const(&fe->fe_f1, FPU_CONST_1);
r = fpu_add(fe);
/* sqrt(1-x^2) */
CPYFPN(&fe->fe_f2, r);
r = fpu_sqrt(fe);
/* x/sqrt */
CPYFPN(&fe->fe_f2, r);
CPYFPN(&fe->fe_f1, &x);
r = fpu_div(fe);
/* arctan */
CPYFPN(&fe->fe_f2, r);
return fpu_atan(fe);
}
double atan( double ang )
{
extern double fpu_atan(double);
return fpu_atan(ang);
}
long double atanl(long double x){
return fpu_atan(x);
}
double atan(double x){
return (double)fpu_atan(x);
}
float atanf(float x){
return (float)fpu_atan(x);
}
