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| 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 | 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x | /**
* @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 ibetaPowerTerms = require( './ibeta_power_terms.js' );
// MAIN //
/**
* Computes the partial derivative with respect to x of the incomplete beta function.
*
* @private
* @param {Probability} x - input value (0 < x <= 1)
* @param {PositiveNumber} a - first parameter
* @param {PositiveNumber} b - second parameter (must be greater than 1)
* @returns {number} value of the partial derivative
*/
function ibetaDerivative( x, a, b ) {
var f1;
var y;
if ( x === 1.0 ) {
return 0.0;
}
// Regular cases:
f1 = ibetaPowerTerms( a, b, x, 1.0 - x, true );
y = ( 1.0 - x ) * x;
f1 /= y;
return f1;
}
// EXPORTS //
module.exports = ibetaDerivative;
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