@stdlib/math-base-special-powm1
v0.3.2TypeScript
Evaluate bˣ - 1.
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Published by The Stdlib Authors
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powm1
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> Evaluate bˣ - 1.
When b is close to 1 and/or x is small, this implementation is more accurate than naively computing bˣ minus 1.
Installation
``bash`
npm install @stdlib/math-base-special-powm1
Usage
`javascript`
var powm1 = require( '@stdlib/math-base-special-powm1' );
#### powm1( b, x )
Evaluates bˣ - 1.
`javascript
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
`javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var powm1 = require( '@stdlib/math-base-special-powm1' );
var opts = {
'dtype': 'float64'
};
var b = discreteUniform( 100, 0, 10, opts );
var x = discreteUniform( 100, -5, 5, opts );
logEachMap( '%d^%d - 1 = %0.4f', b, x, powm1 );
`
*
C APIs
$3
`c`
#include "stdlib/math/base/special/powm1.h"
#### stdlib_base_powm1( b, x )
Evaluates bˣ - 1.
`c
double out = stdlib_base_powm1( 3.141592653589793, 5.0 );
// returns ~305.0197
out = stdlib_base_powm1( 4.0, 0.5 );
// returns 1.0
`
The function accepts the following arguments:
- b: [in] double base.[in] double
- x: exponent.
`c`
double stdlib_base_powm1( const double b, const double x );
$3
`c
#include "stdlib/math/base/special/powm1.h"
#include
#include
int main( void ) {
double out;
double b;
double x;
int i;
for ( i = 0; i < 100; i++ ) {
b = ( ( (double)rand() / (double)RAND_MAX ) * 10.0 );
x = ( ( (double)rand() / (double)RAND_MAX ) * 10.0 ) - 5.0;
out = stdlib_base_powm1( b, x );
printf( "powm1(%lf, %lf) = %lf\n", b, x, out );
}
}
`
*
See Also
- [@stdlib/math-base/special/pow][@stdlib/math/base/special/pow]: exponential function.
*
Notice
This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].
#### Community
[![Chat][chat-image]][chat-url]
---
Copyright
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[deno-readme]: https://github.com/stdlib-js/math-base-special-powm1/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/math-base-special-powm1/tree/umd
[umd-readme]: https://github.com/stdlib-js/math-base-special-powm1/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/math-base-special-powm1/tree/esm
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