NAME

cabs cabsf cabsl — return a complex absolute value

SYNOPSIS

#include <complex.h>

double cabs(double complex z);
float cabsf(float complex z);
long double cabsl(long double complex z);

DESCRIPTION

[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2024 defers to the ISO C standard.

These functions shall compute the complex absolute value (also called norm, modulus, or magnitude) of z.

RETURN VALUE

These functions shall return the complex absolute value.

[MXC] cabs ( x + iy), cabs ( y + ix), and cabs ( x - iy) shall return exactly the same value.

If z is ±0 ± i 0, +0 shall be returned.

If the real or imaginary part of z is ±Inf, +Inf shall be returned, even if the other part is NaN.

If the real or imaginary part of z is NaN and the other part is not ±Inf, NaN shall be returned.

ERRORS

No errors are defined.

The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

XBD <complex.h>

CHANGE HISTORY

First released in Issue 6. Derived from the ISO/IEC 9899:1999 (“ISO C99”) standard.

Issue 8

Austin Group Defect 1302 is applied, aligning these functions with the ISO/IEC 9899:2018 standard.

End of informative text.