# casinh(), casinhf(), casinhl()

Compute the complex inverse hyperbolic sine

## Synopsis:

```#include <complex.h>

double complex casinh( double complex z );

float complex casinhf( float complex z );

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

## Arguments:

z
The value that you want to get the complex inverse hyperbolic sine of.

## Library:

libm

Use the -l m option to qcc to link against this library.

## Description:

These functions compute the complex inverse hyperbolic sine 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 casinh(), casinhf(), or casinhl().
• On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

## Returns:

The complex inverse hyperbolic sine of z.

If z is: These functions return: Errors:
0 + 0i 0 + 0i
x + Infi (for any positive finite x) Inf + (π/2)i
x + NaNi (for any finite x) NaN + NaNi
Inf + yi (for any positive finite y) Inf + 0i
Inf + Infi Inf + (π/4)i
Inf + NaNi Inf + NaNi
NaN + 0i NaN + 0i
NaN + yi (for any finite nonzero y) NaN + NaNi
NaN + Infi ±Inf ± NaNi, where the sign of the real part is unspecified
NaN + NaNi NaN + NaNi

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.

## Classification:

Safety:
Cancellation point No
Interrupt handler No
Signal handler No