@stdlib/math-base-special-factorial
v0.3.0
Published
Evaluate a factorial.
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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-factorial
Usage
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 NaN
Examples
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 ~-3.545
The function accepts the following arguments:
- x:
[in] double
input 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.