README

powm1

$NPM version$ $Build Status$ $Coverage Status$ $dependencies$

Evaluate bˣ - 1.

$Exponential function minus one$

When b is close to 1 and/or x is small, this implementation is more accurate than naively computing bˣ minus 1.

Installation

npm install @stdlib/math-base-special-powm1

Usage

var powm1 = require( '@stdlib/math-base-special-powm1' );

powm1( b, x )

Evaluates bˣ - 1.

var y = powm1( 2.0, 3.0 );
// returns 7.0

y = powm1( 4.0, 0.5 );
// returns 1.0

y = powm1( 0.0, 100.0 );
// returns -1.0

y = powm1( 100.0, 0.0 );
// returns 0.0

y = powm1( 0.0, 0.0 );
// returns 0.0

y = powm1( 3.141592653589793, 5.0 );
// returns ~305.0197

y = powm1( NaN, 3.0 );
// returns NaN

y = powm1( 5.0, NaN );
// returns NaN

Examples

var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var powm1 = require( '@stdlib/math-base-special-powm1' );

var b;
var x;
var y;
var i;

for ( i = 0; i < 100; i++ ) {
    b = round( randu()*10.0 );
    x = round( randu()*10.0 ) - 5.0;
    y = powm1( b, x );
    console.log( '%d^%d - 1 = %d', b, x, y );
}

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

License

See LICENSE.

@stdlib/math-base-special-powm1

Usage no npm install needed!