Trigamma

Trigamma function.

The trigamma function ψ^(1) is the derivative of the digamma function.

Installation

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

Usage

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

trigamma( x )

Evaluates the trigamma function.

var v = trigamma( -2.5 );
// returns ~9.539

v = trigamma( 1.0 );
// returns ~1.645

v = trigamma( 10.0 );
// returns ~0.105

If x is 0 or a negative integer, the function returns NaN.

var v = trigamma( 0.0 );
// returns NaN

v = trigamma( -1.0 );
// returns NaN

v = trigamma( -2.0 );
// returns NaN

If provided NaN, the function returns NaN.

var v = trigamma( NaN );
// returns NaN

Examples

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

var x;
var v;
var i;

for ( i = 0; i < 10; i++ ) {
    x = (randu()*100.0) - 50.0;
    v = trigamma( x );
    console.log( 'x: %d, ψ^(1)(x): %d', x, v );
}

See Also

• @stdlib/math-base/special/digamma: digamma function.
• @stdlib/math-base/special/gamma: gamma 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.

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Copyright

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