stdlib-js
<summary>
About stdlib...
</summary>
We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.
The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.
When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.
To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!
betaincinv
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
Inverse of the [incomplete beta function][incomplete-beta-function].
bash
npm install @stdlib/math-base-special-betaincinv
javascript
var betaincinv = require( '@stdlib/math-base-special-betaincinv' );
#### betaincinv( p, a, b[, upper] )
Inverts the regularized [incomplete beta function][incomplete-beta-function]. Contrary to the more commonly used definition, in this implementation the first parameter is the probability p and the second and third parameter are a and b. By default, the function inverts the lower regularized [incomplete beta function][incomplete-beta-function]. To invert the upper function instead, set the upper argument to true.
javascript
var y = betaincinv( 0.2, 3.0, 3.0 );
// returns ~0.327
y = betaincinv( 0.4, 3.0, 3.0 );
// returns ~0.446
y = betaincinv( 0.4, 3.0, 3.0, true );
// returns ~0.554
y = betaincinv( 0.4, 1.0, 6.0 );
// returns ~0.082
y = betaincinv( 0.8, 1.0, 6.0 );
// returns ~0.235
If provided NaN as any argument, the function returns NaN.
javascript
var y = betaincinv( NaN, 1.0, 1.0 );
// returns NaN
y = betaincinv( 0.5, NaN, 1.0 );
// returns NaN
y = betaincinv( 0.5, 1.0, NaN );
// returns NaN
If provided a value outside [0,1] for p, the function returns NaN.
javascript
var y = betaincinv( 1.2, 1.0, 1.0 );
// returns NaN
y = betaincinv( -0.5, 1.0, 1.0 );
// returns NaN
If provided a nonpositive a, the function returns NaN.
javascript
var y = betaincinv( 0.5, -2.0, 2.0 );
// returns NaN
y = betaincinv( 0.5, 0.0, 2.0 );
// returns NaN
If provided a nonpositive b, the function returns NaN.
javascript
var y = betaincinv( 0.5, 2.0, -2.0 );
// returns NaN
y = betaincinv( 0.5, 2.0, 0.0 );
// returns NaN
javascript
var randu = require( '@stdlib/random-base-randu' );
var betaincinv = require( '@stdlib/math-base-special-betaincinv' );
var i;
var p;
var a;
var b;
for ( i = 0; i < 100; i++ ) {
p = randu();
a = randu() * 10.0;
b = randu() * 10.0;
console.log( 'p: %d, \t a: %d, \t b: %d, \t f(p,a,b): %d', p.toFixed( 4 ), a.toFixed( 4 ), b.toFixed( 4 ), betaincinv( p, a, b ) );
}
@stdlib/math-base/special/beta][@stdlib/math/base/special/beta]: beta function.
- [@stdlib/math-base/special/betainc][@stdlib/math/base/special/betainc]: incomplete beta function.
- [@stdlib/math-base/special/betaln][@stdlib/math/base/special/betaln]: natural logarithm of the beta function.
