exp(), expf(), expl()

Compute the exponential function of a number

Synopsis:

#include <math.h>

double exp( double x );

float expf( float x );

long double expl( long double x );

Arguments:

x
The number for which you want to calculate the exponential.

Library:

libm

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

Description:

These functions compute the exponential function of x (e x ).

A range error occurs if the magnitude of x is too large.

Returns:

The exponential value of x. For a correct value that would cause an underflow, these functions return 0.0.

If an error occurs, these functions return 0, but this is also a valid mathematical result. If you want to check for errors, set errno to 0, call the function, and then check errno again. These functions don't change errno if no errors occurred.

Examples:

#include <stdio.h>
#include <math.h>
#include <stdlib.h>

int main( void )
{
    printf( "%f\n", exp(.5) );

    return EXIT_SUCCESS;
}

produces the output:

1.648721

Classification:

ANSI, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler No
Signal handler No
Thread Yes

Caveats:

The value of expm1(x) may be more accurate than exp(x) - 1.0 for small values of x.

Last modified: 2013-12-23

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