@stdlib/stats-base-dists-degenerate-quantile/lib/main.js

Degenerate distribution quantile function.

/**
* @license Apache-2.0
*
* Copyright (c) 2018 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

'use strict';

// MODULES //

var isnan = require( '@stdlib/math-base-assert-is-nan' );


// MAIN //

/**
* Evaluates the quantile function for a degenerate distribution centered at `mu`.
*
* @param {Probability} p - input value
* @param {number} mu - constant value of the distribution
* @returns {number} evaluated quantile function
*
* @example
* var y = quantile( 0.5, 2.0 );
* // returns 2.0
*
* @example
* var y = quantile( 0.9, 4.0 );
* // returns 4.0
*
* @example
* var y = quantile( 1.1, 0.0 );
* // returns NaN
*
* @example
* var y = quantile( -0.2, 0.0 );
* // returns NaN
*
* @example
* var y = quantile( NaN, 0.0 );
* // returns NaN
*
* @example
* var y = quantile( 0.0, NaN );
* // returns NaN
*/
function quantile( p, mu ) {
	if ( isnan( p ) || p < 0.0 || p > 1.0 ) {
		return NaN;
	}
	return mu;
}


// EXPORTS //

module.exports = quantile;