Quick Navigator

 Search Site Miscellaneous Server Agreement Year 2038 Credits

# Manual Reference Pages  -  CEXP (3)

### NAME

cexp, cexpf - complex exponential functions

Library
Synopsis
Description
Return Values
Standards

.Lb libm

### SYNOPSIS

.In complex.h double complex cexp double complex z float complex cexpf float complex z

### DESCRIPTION

The cexp and cexpf functions compute the complex exponential of z, also known as cis( z).

### RETURN VALUES

For real numbers x and y, cexp behaves according to Euler’s formula:
```
cexp x + I*y
=

(e **

x *

cos(

y+())

I
*

e **

x
*

sin(

y))

```

Generally speaking, infinities, zeroes and NaNs are handled as would be expected from this identity given the usual rules of floating-point arithmetic. However, care is taken to avoid generating NaNs when they are not deserved. For example, mathematically we expect that
.Fo cimag cexp x + I*0 Fc = 0 regardless of the value of x, and cexp preserves this identity even if x is oo or NaN. Likewise, cexp -oo + I*y = 0 and
.Fo creal cexp oo + I*y Fc = oo for any y (even though the latter property is only mathematically true for representable y.) If y is not finite, the sign of the result is indeterminate.