CTAN(3) | Library Functions Manual | CTAN(3)

# NAME

`ctan`, `ctanf`, `ctanl` — complex circular tangent

# SYNOPSIS

Math Library (libm, -lm)
`#include <complex.h>`

double complex
`ctan`(double complex z);

float complex
`ctanf`(float complex z);

long double complex
`ctanl`(long double complex z);

# DESCRIPTION

The `ctan`(), `ctanf`() and `ctanl`() functions compute the complex circular tangent of z.

If z = x + iy, then

    ctan(z) = (sin(2x) + i sinh(2y)) / (cos(2x) + cosh(2y)).

On the real axis the denominator is zero at odd multiples of Pi/2. The denominator is evaluated by its Taylor series near these points.

    ctan(z) = -i ctanh(iz).

# RETURN VALUES

The `ctan`(), `ctanf`() and `ctanl`() functions return the complex circular tangent of z.

# SEE ALSO

ccos(3), csin(3)

# STANDARDS

The `ctan`(), `ctanf`() and `ctanl`() functions conform to ISO/IEC 9899:1999 (“ISO C99”).

June 7, 2025 | Debian