stdlib-js
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factorial
Factorial function.
The factorial function may be defined as the product
or according to the recurrence relation
Following the convention for an empty product, in all definitions,
The Gamma function extends the factorial function for non-integer values.
The factorial of a negative integer is not defined.
Installation
npm install @stdlib/math-base-special-factorialUsage
var factorial = require( '@stdlib/math-base-special-factorial' );factorial( x )
Evaluates the factorial function.
var v = factorial( 3.0 );
// returns 6.0
v = factorial( -1.5 );
// returns ~-3.545
v = factorial( -0.5 );
// returns ~1.772
v = factorial( 0.5 );
// returns ~0.886
v = factorial( -10.0 );
// returns NaN
v = factorial( 171.0 );
// returns Infinity
v = factorial( NaN );
// returns NaNExamples
var incrspace = require( '@stdlib/array-base-incrspace' );
var factorial = require( '@stdlib/math-base-special-factorial' );
var x = incrspace( -10.0, 100.0, 1.0 );
var i;
for ( i = 0; i < x.length; i++ ) {
console.log( 'x: %d, f(x): %d', x[ i ], factorial( x[ i ] ) );
}C APIs
Usage
#include "stdlib/math/base/special/factorial.h"stdlib_base_factorial( x )
Evaluates the factorial function.
double out = stdlib_base_factorial( 3.0 );
// returns 6.0
out = stdlib_base_factorial( -1.5 );
// returns ~-3.545The function accepts the following arguments:
- x:
[in] doubleinput value.
double stdlib_base_factorial( const double n );Examples
#include "stdlib/math/base/special/factorial.h"
#include <stdio.h>
int main( void ) {
const double x[] = { 2.0, 3.0, 5.0, 8.0 };
double y;
int i;
for ( i = 0; i < 4; i++ ) {
y = stdlib_base_factorial( x[ i ] );
printf( "factorial(%lf) = %lf\n", x[ i ], y );
}
}See Also
@stdlib/math-base/special/factorialln: evaluate the natural logarithm of the factorial function.
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.
Copyright
Copyright © 2016-2024. The Stdlib Authors.