'\" t .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de) .\" and Copyright (C) 2011 Michael Kerrisk .\" .\" SPDX-License-Identifier: GPL-1.0-or-later .\" .TH catan 3 2024-06-15 "Linux man-pages 6.9.1" .SH NAME catan, catanf, catanl \- complex arc tangents .SH LIBRARY Math library .RI ( libm ", " \-lm ) .SH SYNOPSIS .nf .B #include .P .BI "double complex catan(double complex " z ); .BI "float complex catanf(float complex " z ); .BI "long double complex catanl(long double complex " z ); .fi .SH DESCRIPTION These functions calculate the complex arc tangent of .IR z . If \fIy\~=\~catan(z)\fP, then \fIz\~=\~ctan(y)\fP. The real part of .I y is chosen in the interval [\-pi/2, pi/2]. .P One has: .P .in +4n .EX catan(z) = (clog(1 + i * z) \- clog(1 \- i * z)) / (2 * i) .EE .in .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 catan (), .BR catanf (), .BR catanl () T} Thread safety MT-Safe .TE .SH STANDARDS C11, POSIX.1-2008. .SH HISTORY glibc 2.1. C99, POSIX.1-2001. .SH EXAMPLES .\" SRC BEGIN (catan.c) .EX /* Link with "\-lm" */ \& #include #include #include #include \& int main(int argc, char *argv[]) { double complex z, c, f; double complex i = I; \& if (argc != 3) { fprintf(stderr, "Usage: %s \[rs]n", argv[0]); exit(EXIT_FAILURE); } \& z = atof(argv[1]) + atof(argv[2]) * I; \& c = catan(z); printf("catan() = %6.3f %6.3f*i\[rs]n", creal(c), cimag(c)); \& f = (clog(1 + i * z) \- clog(1 \- i * z)) / (2 * i); printf("formula = %6.3f %6.3f*i\[rs]n", creal(f), cimag(f)); \& exit(EXIT_SUCCESS); } .EE .\" SRC END .SH SEE ALSO .BR ccos (3), .BR clog (3), .BR ctan (3), .BR complex (7)