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