csqrt, csqrtf, csqrtl

Math library (libm, -lm)

#include <complex.h>

double complex csqrt(double complex z);
float complex csqrtf(float complex z);
long double complex csqrtl(long double complex z);

These functions calculate the complex square root of z, with a branch cut along the negative real axis. (That means that csqrt(-1+eps*I) will be close to I while csqrt(-1-eps*I) will be close to -I, if eps is a small positive real number.)

For an explanation of the terms used in this section, see attributes(7).

C11, POSIX.1-2008.

glibc 2.1. C99, POSIX.1-2001.

cabs(3), cexp(3), complex(7)