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 | 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 3800x 3800x 3800x 3800x 3800x 3800x 3800x 3800x 3800x 3800x 3800x 3800x 3800x 300x 300x 300x 3800x 3500x 3500x 3500x 3500x 3800x 3800x 3945x 3964x 3964x 3945x 3945x 3945x 3945x 3945x 3945x 3945x 3800x 3800x 3945x 3800x 3800x 2x 2x 2x 2x 2x | /**
* @license Apache-2.0
*
* Copyright (c) 2021 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 ln = require( '@stdlib/math/base/special/ln' );
var sqrt = require( '@stdlib/math/base/special/sqrt' );
var pow = require( '@stdlib/math/base/special/pow' );
// VARIABLES //
var ONE_THIRD = 1.0 / 3.0;
// MAIN //
/**
* Returns a pseudorandom number drawn from a gamma distribution with rate parameter equal to 1.0 and shape parameter equal to `alpha`.
*
* @private
* @param {PRNG} randu - PRNG for uniformly distributed numbers
* @param {PRNG} randn - PRNG for standard normally distributed numbers
* @param {PositiveNumber} alpha - shape parameter
* @returns {PositiveNumber} pseudorandom number
*/
function standardGamma( randu, randn, alpha ) {
var flg;
var x2;
var v0;
var v1;
var c;
var d;
var x;
var s;
var u;
var v;
if ( alpha < 1.0 ) {
d = alpha + 1.0 - ONE_THIRD;
c = 1.0 / sqrt( 9.0*d );
s = pow( randu(), 1.0/alpha );
} else {
d = alpha - ONE_THIRD;
c = 1.0 / sqrt( 9.0*d );
s = 1.0;
}
flg = true;
while ( flg ) {
do {
x = randn();
v = 1.0 + (c*x);
} while ( v <= 0.0 );
v *= v * v;
x2 = x * x;
v0 = 1.0 - (0.331*x2*x2);
v1 = (0.5*x2) + (d*( 1.0-v+ln(v) ));
u = randu();
if ( u < v0 || ln( u ) < v1 ) {
flg = false;
}
}
return d * v * s;
}
// EXPORTS //
module.exports = standardGamma;
|