clog(3) [redhat man page]

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

NAME

       clog, clogf, clogl - natural logarithm of a complex number

SYNOPSIS

       #include <complex.h>

       double complex clog(double complex z);
       float complex clogf(float complex z);
       long double complex clogl(long double complex z);

       Link with -lm.

DESCRIPTION

       These functions calculate the complex natural logarithm of z, with a branch cut along the negative real axis.

       The  logarithm clog() is the inverse function of the exponential cexp(3).  Thus, if y = clog(z), then z = cexp(y).  The imaginary part of y
       is chosen in the interval [-pi,pi].

       One has:

           clog(z) = log(cabs(z)) + I * carg(z)

       Note that z close to zero will cause an overflow.

VERSIONS

       These functions first appeared in glibc in version 2.1.

ATTRIBUTES

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

       +-------------------------+---------------+---------+
       |Interface                | Attribute     | Value   |
       +-------------------------+---------------+---------+
       |clog(), clogf(), clogl() | Thread safety | MT-Safe |
       +-------------------------+---------------+---------+
CONFORMING TO

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

SEE ALSO

       cabs(3), cexp(3), clog10(3), clog2(3), complex(7)

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

                                                                    2017-09-15                                                             CLOG(3)

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

NAME

       catan, catanf, catanl - complex arc tangents

SYNOPSIS

       #include <complex.h>

       double complex catan(double complex z);
       float complex catanf(float complex z);
       long double complex catanl(long double complex z);

       Link with -lm.

DESCRIPTION

       These  functions  calculate the complex arc tangent of z.  If y = catan(z), then z = ctan(y).  The real part of y is chosen in the interval
       [-pi/2,pi/2].

       One has:

	   catan(z) = (clog(1 + i * z) - clog(1 - i * z)) / (2 * i)

VERSIONS

       These functions first appeared in glibc in version 2.1.

ATTRIBUTES

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

       +----------------------------+---------------+---------+
       |Interface		    | Attribute     | Value   |
       +----------------------------+---------------+---------+
       |catan(), catanf(), catanl() | Thread safety | MT-Safe |
       +----------------------------+---------------+---------+
CONFORMING TO

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

EXAMPLE

       /* Link with "-lm" */

       #include <complex.h>
       #include <stdlib.h>
       #include <unistd.h>
       #include <stdio.h>

       int
       main(int argc, char *argv[])
       {
	   double complex z, c, f;
	   double complex i = I;

	   if (argc != 3) {
	       fprintf(stderr, "Usage: %s <real> <imag>
", argv[0]);
	       exit(EXIT_FAILURE);
	   }

	   z = atof(argv[1]) + atof(argv[2]) * I;

	   c = catan(z);
	   printf("catan() = %6.3f %6.3f*i
", creal(c), cimag(c));

	   f = (clog(1 + i * z) - clog(1 - i * z)) / (2 * i);
	   printf("formula = %6.3f %6.3f*i
", creal(f2), cimag(f2));

	   exit(EXIT_SUCCESS);
       }

SEE ALSO

       ccos(3), clog(3), ctan(3), complex(7)

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

								    2015-04-19								  CATAN(3)