CABS(3) Linux Programmer's Manual CABS(3)

cabs, cabsf, cabsl - absolute value of a complex number

#include <complex.h>
double cabs(double complex z);
float cabsf(float complex z);
long double cabsl(long double complex z);
Link with -lm.

These functions return the absolute value of the complex number z. The result is a real number.

These functions first appeared in glibc in version 2.1.

For an explanation of the terms used in this section, see attributes(7).
Interface Attribute Value
cabs (), cabsf (), cabsl () Thread safety MT-Safe

C99, POSIX.1-2001, POSIX.1-2008.

The function is actually an alias for hypot(a, b) (or, equivalently, sqrt(a*a + b*b)).

abs(3), cimag(3), hypot(3), complex(7)