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 | 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 4016x 4016x 4016x 4016x 4016x 4016x 4006x 4016x 12x 12x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4004x 4009x 1x 1x 4009x 8x 8x 4000x 4009x 4016x 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 isNonNegativeInteger = require( '@stdlib/math/base/assert/is-nonnegative-integer' );
var constantFunction = require( '@stdlib/utils/constant-function' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var ibetaDerivative = require( './ibeta_derivative.js' );
// MAIN //
/**
* Returns a function for evaluating the probability mass function (PMF) for a negative binomial distribution with number of successes until experiment is stopped `r` and success probability `p`.
*
* @param {PositiveNumber} r - number of successes until experiment is stopped
* @param {Probability} p - success probability
* @returns {Function} PMF
*
* @example
* var pmf = factory( 10, 0.5 );
* var y = pmf( 3.0 );
* // returns ~0.027
*
* y = pmf( 5.0 );
* // returns ~0.061
*/
function factory( r, p ) {
if (
isnan( r ) ||
isnan( p ) ||
r <= 0.0 ||
p <= 0.0 ||
p > 1.0
) {
return constantFunction( NaN );
}
return pmf;
/**
* Evaluates the probability mass function (PMF) for a negative binomial distribution.
*
* @private
* @param {number} x - input value
* @returns {Probability} evaluated PMF
*
* @example
* var y = pmf( 2.0 );
* // returns <number>
*/
function pmf( x ) {
if ( isnan( x ) ) {
return NaN;
}
if ( !isNonNegativeInteger( x ) ) {
return 0.0;
}
return ( p / ( r + x ) ) * ibetaDerivative( p, r, x + 1.0 );
}
}
// EXPORTS //
module.exports = factory;
|