stdlib-js
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Kernel Betainc
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
[Incomplete beta function][incomplete-beta-function] and its first derivative.
bash
npm install @stdlib/math-base-special-kernel-betainc
javascript
var kernelBetainc = require( '@stdlib/math-base-special-kernel-betainc' );
#### kernelBetainc( x, a, b, regularized, upper )
Evaluates the [incomplete beta function][incomplete-beta-function] and its first derivative for parameters x, a > 0 and b > 0. The regularized and upper boolean parameters are used to specify whether to evaluate the regularized or non-regularized and the upper or lower incomplete beta functions, respectively.
javascript
var out = kernelBetainc( 0.8, 1.0, 0.3, false, false );
// returns [ ~1.277, ~0.926 ]
out = kernelBetainc( 0.2, 1.0, 2.0, true, false );
// returns [ 0.36, 1.6 ]
out = kernelBetainc( 0.2, 1.0, 2.0, true, true );
// returns [ 0.64, 1.6 ]
If provided NaN for x, a, or b, the function returns [ NaN, NaN ].
javascript
var out = kernelBetainc( NaN, 1.0, 1.0, true, true );
// returns [ NaN, NaN ]
out = kernelBetainc( 0.8, NaN, 1.0, true, true );
// returns [ NaN, NaN ]
out = kernelBetainc( 0.8, 1.0, NaN, true, true );
// returns [ NaN, NaN ]
If x is outside the interval [0,1], the function returns [ NaN, NaN ].
javascript
var out = kernelBetainc( 1.5, 1.0, 1.0, true, true );
// returns [ NaN, NaN ]
out = kernelBetainc( -0.5, 1.0, 1.0, true, true );
// returns [ NaN, NaN ]
If a or b is negative, the function returns [ NaN, NaN ].
javascript
var out = kernelBetainc( 0.5, -2.0, 2.0, true, true );
// returns [ NaN, NaN ]
out = kernelBetainc( 0.5, 2.0, -2.0, true, true );
// returns [ NaN, NaN ]
#### kernelBetainc.assign( x, a, b, regularized, upper, out, stride, offset )
Evaluates the [incomplete beta function][incomplete-beta-function] and its first derivative for parameters x, a > 0 and b > 0 and assigns results to a provided output array.
javascript
var Float64Array = require( '@stdlib/array-float64' );
var out = new Float64Array( 2 );
var v = kernelBetainc.assign( 0.2, 1.0, 2.0, true, true, out, 1, 0 );
// returns <Float64Array>[ 0.64, 1.6 ]
var bool = ( v === out );
// returns true
The offset parameter specifies the index of the first output array element, and the stride parameter specifies the stride length between consecutive output array elements.
javascript
var randu = require( '@stdlib/random-base-randu' );
var kernelBetainc = require( '@stdlib/math-base-special-kernel-betainc' );
var out;
var i;
var x;
var a;
var b;
out = [ 0.0, 0.0 ];
for ( i = 0; i < 100; i++ ) {
x = randu();
a = randu() * 10.0;
b = randu() * 10.0;
kernelBetainc( x, a, b, true, false, out, 1, 0 );
console.log( 'x: %d, \t a: %d, \t b: %d, \t f(x,a,b): %d, \t f^1(x,a,b): %d', x.toFixed( 4 ), a.toFixed( 4 ), b.toFixed( 4 ), out[ 0 ].toFixed( 4 ), out[ 1 ].toFixed( 4 ) );
}
@stdlib/math-base/special/betainc][@stdlib/math/base/special/betainc]: incomplete beta function.
