casin

Complex circular arc sine.

SYNOPSIS:

void casin();
cmplx z, w;

casin(&z, &w);

DESCRIPTION:

Inverse complex sine:
                              2
w = -i clog(iz + csqrt(1 - z )).

ACCURACY:
                      Relative error:
arithmetic   domain     # trials      peak         rms
    DEC       -10,+10     10100       2.1e-15     3.4e-16
    IEEE      -10,+10     30000       2.2e-14     2.7e-15

Larger relative error can be observed for z near zero. Also tested by csin(casin(z)) = z.