NAME

ctan, ctanf, ctanl — complex tangent functions

SYNOPSIS

#include <complex.h>

double complex ctan(double complex z);
float complex ctanf(float complex z);
long double complex ctanl(long double complex z);


DESCRIPTION

^[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2024 defers to the ISO C standard.

These functions shall compute the complex tangent of z.

RETURN VALUE

These functions shall return the complex tangent value.

^[MXC] ctan(conj(iz)), ctanf(conjf(iz)), and ctanl(conjl(iz)) shall return exactly the same value as conj(ctan(iz)), conjf(ctanf(iz)), and conjl(ctanl(iz)), respectively, and ctan(-iz), ctanf(-iz), and ctanl(-iz) shall return exactly the same value as -ctan(iz), -ctanf(iz), and -ctanl(iz), respectively, including for the special values of iz below.

If iz is +0 + i0, -i (+0 + i0) shall be returned.

If iz is 0 + iInf, -i (0 + iNaN) shall be returned and the invalid floating-point exception shall be raised.

If iz is x + iInf where x is non-zero and finite, -i (NaN + iNaN) shall be returned and the invalid floating-point exception shall be raised.

If iz is 0 + iNaN, -i (0 + iNaN) shall be returned.

If iz is x + iNaN where x is non-zero and finite, -i (NaN + iNaN) shall be returned and the invalid floating-point exception may be raised.

If iz is +Inf + iy where y is positive-signed and finite, -i (1 + i0 sin(2y)) shall be returned.

If iz is +Inf + iInf, -i (1 ± i0) shall be returned; the sign of the real part of the result is unspecified.

If iz is +Inf + iNaN, -i (1 ± i0) shall be returned; the sign of the real part of the result is unspecified.

If iz is NaN + i0, -i (NaN + i0) shall be returned.

If iz is NaN + iy where y is any non-zero number, -i (NaN + iNaN) shall be returned and the invalid floating-point exception may be raised.

If iz is NaN + iNaN, -i (NaN + iNaN) shall be returned.

ERRORS

No errors are defined.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

The MXC special cases for ctan() are derived from those for ctanh() by applying the formula ctan(z) = -ictanh(iz).

FUTURE DIRECTIONS

None.

SEE ALSO

catan, ctanh

XBD <complex.h>

CHANGE HISTORY

First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.

Issue 8

Austin Group Defect 1302 is applied, aligning these functions with the ISO/IEC 9899:2018 standard.