Compute the complex arc tangent
Synopsis:
#include <complex.h>
double complex catan( double complex z );
float complex catanf( float complex z );
long double complex catanl( long double complex z );
Arguments:
 z
 The value that you want to get the complex arc tangent of.
Library:
 libm
 The generalpurpose math library.
 libmsve
 (QNX Neutrino 7.1 or later)
A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.
Your system requirements will determine how you should work with these libraries:
 If you want only selected processes to run with the SVE version, you can include both libraries in your OS image
and use the l m or l msve option to
qcc
to link explicitly against the appropriate one.
 If you want all processes to use the SVE version, include libmsve.so in your OS image
and set up a symbolic link from libm.so to libmsve.so.
Use the l m option to
qcc
to link against the library.
Note:
Compile your program with the fnobuiltin option to prevent the compiler from using a
builtin version of the function.
Description:
These functions compute the complex arc tangent of z,
with branch cuts outside the interval [−i,+i] along the imaginary axis.
To check for error situations, use
feclearexcept()
and
fetestexcept().
For example:
 Call feclearexcept(FE_ALL_EXCEPT) before calling
catan(), catanf(), or catanl().
 On return, if fetestexcept(FE_ALL_EXCEPT)
is nonzero, then an error has occurred.
Returns:
The complex arc tangent of z, in the range of a strip unbounded along the imaginary axis
and in the interval [−π/2; +π/2] along the real axis.
Errors and special cases are handled as if the operation were implemented as
i * catanh(i * z).
These functions raise FE_INEXACT if the FPU reports that
the result can't be exactly represented as a floatingpoint number.
Classification:
C11,
POSIX 1003.1
Safety: 

Cancellation point 
No 
Interrupt handler 
Yes 
Signal handler 
Yes 
Thread 
Yes 