ctan, ctanf, ctanl — complex tangent functions
#include <complex.h>
double complex ctan(double complex z);
float complex ctanf(float complex z);
long double complex ctanl(long double complex z);
[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.
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.
No errors are defined.
None.
None.
The MXC special cases for ctan() are derived from those for ctanh() by applying the formula ctan(z) = -ictanh(iz).
None.
XBD <complex.h>
First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.
Austin Group Defect 1302 is applied, aligning these functions with the ISO/IEC 9899:2018 standard.
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