Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 | 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 4009x 4009x 4009x 4009x 4007x 4009x 5x 5x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4003x 4003x 1x 1x 4003x 1x 1x 4001x 4001x 4003x 4009x 3x 3x 3x 3x 3x | /**
* @license Apache-2.0
*
* Copyright (c) 2026 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 constantFunction = require( '@stdlib/utils/constant-function' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var sqrt = require( '@stdlib/math/base/special/sqrt' );
var exp = require( '@stdlib/math/base/special/exp' );
var PI = require( '@stdlib/constants/float64/pi' );
// MAIN //
/**
* Returns a function for evaluating the probability density function (PDF) for a half-normal distribution.
*
* @param {PositiveNumber} sigma - scale parameter
* @returns {Function} function to evaluate the probability density function
*
* @example
* var pdf = factory( 1.0 );
* var y = pdf( 2.0 );
* // returns ~0.108
*
* y = pdf( 1.0 );
* // returns ~0.484
*/
function factory( sigma ) {
var A;
if (
isnan( sigma ) ||
sigma <= 0.0
) {
return constantFunction( NaN );
}
A = sqrt( 2.0 / PI ) / sigma;
return pdf;
/**
* Evaluates the probability density function (PDF) for a half-normal distribution.
*
* @private
* @param {number} x - input value
* @returns {number} evaluated probability density function
*
* @example
* var y = pdf( 0.5 );
* // returns <number>
*/
function pdf( x ) {
var C;
if ( isnan( x ) ) {
return NaN;
}
if ( x < 0.0 ) {
return 0.0;
}
C = x / sigma;
return A * exp( -0.5 * ( C*C ) );
}
}
// EXPORTS //
module.exports = factory;
|