expm1

Compute exp(x) - 1.

Usage

var expm1 = require( '@stdlib/math/base/special/expm1' );

expm1( x )

Computes exp(x) - 1, where exp(x) is the natural exponential function.

var v = expm1( 0.2 );
// returns ~0.221

v = expm1( -9.0 );
// returns ~-1.0

v = expm1( 0.0 );
// returns 0.0

v = expm1( NaN );
// returns NaN

Examples

var uniform = require( '@stdlib/random/array/uniform' );
var logEachMap = require( '@stdlib/console/log-each-map' );
var expm1 = require( '@stdlib/math/base/special/expm1' );

var opts = {
    'dtype': 'float64'
};
var x = uniform( 100, -5.0, 5.0, opts );

logEachMap( 'e^%0.4f - 1 = %0.4f', x, expm1 );

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C APIs

Usage

#include "stdlib/math/base/special/expm1.h"

stdlib_base_expm1( x )

Computes exp(x) - 1, where exp(x) is the natural exponential function.

double out = stdlib_base_expm1( 0.2 );
// returns ~0.221

out = stdlib_base_expm1( -9.0 );
// returns ~-1.0

The function accepts the following arguments:

• x: [in] double input value.

double stdlib_base_expm1( const double x );

Examples

#include "stdlib/math/base/special/expm1.h"
#include <stdlib.h>
#include <stdio.h>

int main( void ) {
    double x;
    double v;
    int i;

    for ( i = 0; i < 100; i++ ) {
        x = ( ( (double)rand() / (double)RAND_MAX ) * 10.0 ) - 5.0;
        v = stdlib_base_expm1( x );
        printf( "e^%lf - 1 = %lf\n", x, v );
    }
}

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See Also

• @stdlib/math/base/special/exp: natural exponential function.
• @stdlib/math/base/special/expm1rel: relative error exponential.