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 86 87 88 89 90 | 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 3x 3x 3014x 3014x 3014x 3014x 3014x 3014x 3014x 3009x 3014x 10x 10x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3003x 1x 1x 3003x 1x 1x 3001x 3003x 3014x 3x 3x 3x 3x 3x | /**
* @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 constantFunction = require( '@stdlib/utils/constant-function' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var pow = require( '@stdlib/math/base/special/pow' );
var ln = require( '@stdlib/math/base/special/ln' );
var NINF = require( '@stdlib/constants/float64/ninf' );
var PI = require( '@stdlib/constants/float64/pi' );
// MAIN //
/**
* Returns a function for evaluating the natural logarithm of the probability density function (PDF) for a lognormal distribution with location parameter `mu` and scale parameter `sigma`.
*
* @param {number} mu - location parameter
* @param {PositiveNumber} sigma - scale parameter
* @returns {Function} logPDF
*
* @example
* var logpdf = factory( 4.0, 2.0 );
* var y = logpdf( 10.0 );
* // returns ~-4.275
*
* y = logpdf( 2.0 );
* // returns ~-3.672
*/
function factory( mu, sigma ) {
var s2;
var A;
var B;
if (
isnan( mu ) ||
isnan( sigma ) ||
sigma <= 0.0
) {
return constantFunction( NaN );
}
s2 = pow( sigma, 2.0 );
A = -0.5 * ln( 2.0 * s2 * PI );
B = -1.0 / ( 2.0 * s2 );
return logpdf;
/**
* Evaluates the natural logarithm of the probability density function (PDF) for a lognormal distribution.
*
* @private
* @param {number} x - input value
* @returns {number} evaluated logPDF
*
* @example
* var y = logpdf( 2.5 );
* // returns <number>
*/
function logpdf( x ) {
if ( isnan( x ) ) {
return NaN;
}
if ( x <= 0.0 ) {
return NINF;
}
return A - ln( x ) + ( B * pow( ln(x) - mu, 2.0 ) );
}
}
// EXPORTS //
module.exports = factory;
|