'\" t .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de) .\" .\" SPDX-License-Identifier: GPL-1.0-or-later .\" .TH creal 3 2023-10-31 "Linux man-pages 6.7" .SH NAME creal, crealf, creall \- get real part of a complex number .SH LIBRARY Math library .RI ( libm ", " \-lm ) .SH SYNOPSIS .nf .B #include .P .BI "double creal(double complex " z ); .BI "float crealf(float complex " z ); .BI "long double creall(long double complex " z ); .fi .SH DESCRIPTION These functions return the real part of the complex number .IR z . .P One has: .P .nf z = creal(z) + I * cimag(z) .fi .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). .TS allbox; lbx lb lb l l l. Interface Attribute Value T{ .na .nh .BR creal (), .BR crealf (), .BR creall () T} Thread safety MT-Safe .TE .SH VERSIONS GCC supports also __real__. That is a GNU extension. .SH STANDARDS C11, POSIX.1-2008. .SH HISTORY glibc 2.1. C99, POSIX.1-2001. .SH SEE ALSO .BR cabs (3), .BR cimag (3), .BR complex (7)