Package Exports
- @stdlib/math-base-special-digamma
- @stdlib/math-base-special-digamma/dist
- @stdlib/math-base-special-digamma/dist/index.js
- @stdlib/math-base-special-digamma/lib/index.js
This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (@stdlib/math-base-special-digamma) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.
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digamma
Digamma function.
The digamma function ψ is the logarithmic derivative of the gamma function, i.e.
Installation
npm install @stdlib/math-base-special-digammaUsage
var digamma = require( '@stdlib/math-base-special-digamma' );digamma( x )
Evaluates the digamma function.
var v = digamma( -2.5 );
// returns ~1.103
v = digamma( 1.0 );
// returns ~-0.577
v = digamma( 10.0 );
// returns ~2.252If x is 0 or a negative integer, the function returns NaN.
var v = digamma( 0.0 );
// returns NaN
v = digamma( -1.0 );
// returns NaN
v = digamma( -2.0 );
// returns NaNIf provided NaN, the function returns NaN.
var v = digamma( NaN );
// returns NaNExamples
var randu = require( '@stdlib/random-base-randu' );
var digamma = require( '@stdlib/math-base-special-digamma' );
var x;
var v;
var i;
for ( i = 0; i < 10; i++ ) {
x = (randu()*10.0) - 5.0;
v = digamma( x );
console.log( 'x: %d, f(x): %d', x, v );
}C APIs
Usage
#include "stdlib/math/base/special/digamma.h"stdlib_base_digamma( x )
Evaluates the digamma function.
double out = stdlib_base_digamma( -2.5 );
// returns ~1.103
out = stdlib_base_digamma( 1.0 );
// returns ~-0.577The function accepts the following arguments:
- x:
[in] doubleinput value.
double stdlib_base_digamma( const double x );Examples
#include "stdlib/math/base/special/digamma.h"
#include <stdlib.h>
#include <stdio.h>
int main( void ) {
const double x[] = { 4.0, -1.5, -0.5, 0.5 };
double y;
int i;
for ( i = 0; i < 4; i++ ) {
y = stdlib_base_digamma( x[ i ] );
printf( "digamma(%lf) = %lf\n", x[ i ], 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.
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