# cexp(), cexpf(), cexpl()

 Updated: October 26, 2022

Compute the complex base-e exponential of a complex number

## Synopsis:

```#include <complex.h>

double complex cexp(double complex z );

float complex cexpf(float complex z );

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

## Arguments:

z
The complex value that you want to compute the complex base-e exponential of.

## Library:

libm
The general-purpose math library.
libm-sve
(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 m-sve option to qcc to link explicitly against the appropriate one.
• If you want all processes to use the SVE version, include libm-sve.so in your OS image and set up a symbolic link from libm.so to libm-sve.so. Use the -l m option to qcc to link against the library.
Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.

## Description:

These functions compute the complex base-e exponential of z. If z = x+iy, the complex exponential is:

```ez = ex cis(y)
= ex (cos(y) + i sin(y))
```

The exponential function is an entire function in the complex plane and has no branch cuts.

To check for error situations, use feclearexcept() and fetestexcept(). For example:

• Call feclearexcept(FE_ALL_EXCEPT) before calling cexp(), cexpf(), or cexpl().
• On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

## Returns:

If no errors occur, the complex base-e exponential of z.

If z is: These functions return: Errors:
±0 + 0i 1 + 0i
x + Infi, for any finite x NaN + NaNi FE_INVALID
x + NaNi, for any finite x NaN + NaNi
Inf + 0i Inf + 0i
-Inf + yi, for any finite y 0 * cis(y)
Inf + yi, for any finite nonzero y Inf * cis(y)
-Inf + Infi ±0 ± 0i, where the signs are unspecified
Inf + Infi ±Inf + NaNi, where the sign of the real part is unspecified FE_INVALID
-Inf + NaNi ±0 ± 0i, where the signs are unspecified
Inf + NaNi ±Inf - NaNi, where the sign of the real part is unspecified
NaN + 0i NaN + 0i
NaN + yi, for any nonzero y NaN + NaNi
NaN + NaNi NaN + NaNi

where cis(y) is cos(y) + i sin(y).

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 Yes
Signal handler Yes