fusl/src/complex/casin.c

#include "libm.h"

// FIXME

/* asin(z) = -i log(i z + sqrt(1 - z*z)) */

double complex casin(double complex z) {
  double complex w;
  double x, y;

  x = creal(z);
  y = cimag(z);
  w = CMPLX(1.0 - (x - y) * (x + y), -2.0 * x * y);
  return clog(CMPLX(-y, x) + csqrt(w));
}