log1p

Evaluate the natural logarithm of 1+x.

Usage

var log1p = require( '@stdlib/math/base/special/log1p' );

log1p( x )

Evaluates the natural logarithm of 1+x.

var v = log1p( 4.0 );
// returns ~1.609

v = log1p( -1.0 );
// returns -Infinity

v = log1p( Infinity );
// returns Infinity

v = log1p( 0.0 );
// returns 0.0

v = log1p( -0.0 );
// returns -0.0

v = log1p( NaN );
// returns NaN

For x < -1, the function returns NaN, as the natural logarithm is not defined for negative numbers.

var v = log1p( -2.0 );
// returns NaN

Examples

var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var log1p = require( '@stdlib/math/base/special/log1p' );

var x;
var i;

for ( i = 0; i < 100; i++ ) {
    x = round( randu() * 100.0 );
    console.log( log1p( x ) );
}