github.com/afumu/libc@v0.0.6/musl/src/complex/casin.c (about)

     1  #include "complex_impl.h"
     2  
     3  // FIXME
     4  
     5  /* asin(z) = -i log(i z + sqrt(1 - z*z)) */
     6  
     7  double complex casin(double complex z)
     8  {
     9  	double complex w;
    10  	double x, y;
    11  
    12  	x = creal(z);
    13  	y = cimag(z);
    14  	w = CMPLX(1.0 - (x - y)*(x + y), -2.0*x*y);
    15  	double complex r = clog(CMPLX(-y, x) + csqrt(w));
    16  	return CMPLX(cimag(r), -creal(r));
    17  }