catan

Section: C Library Functions (3)
Updated: 2022-12-15
Index Return to Main Contents
 

NAME

catan, catanf, catanl - complex arc tangents  

LIBRARY

Math library (libm, -lm)  

SYNOPSIS

#include <complex.h>

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

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 were added in glibc 2.1.  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
catan(), catanf(), catanl() Thread safetyMT-Safe

 

STANDARDS

C99, POSIX.1-2001, POSIX.1-2008.  

EXAMPLES

/* Link with "-lm" */

#include <complex.h> #include <stdio.h> #include <stdlib.h> #include <unistd.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>\n", argv[0]);
        exit(EXIT_FAILURE);
    }


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


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


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


    exit(EXIT_SUCCESS); }  

SEE ALSO

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


 

Index

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
VERSIONS
ATTRIBUTES
STANDARDS
EXAMPLES
SEE ALSO

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Time: 05:03:54 GMT, March 29, 2024