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 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 | 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 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 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.
*
*
* ## Notice
*
* The original C++ code and copyright notice are from the [Boost library]{@link http://www.boost.org/doc/libs/1_85_0/boost/math/special_functions/trigamma.hpp}. The implementation follows the original but has been reformatted and modified for JavaScript.
*
* ```text
* (C) Copyright John Maddock 2006.
*
* Use, modification and distribution are subject to the
* Boost Software License, Version 1.0. (See accompanying file
* LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
* ```
*/
'use strict';
// MODULES //
var floor = require( '@stdlib/math/base/special/floor' );
var sinpi = require( '@stdlib/math/base/special/sinpi' );
var PI_SQUARED = require( '@stdlib/constants/float64/pi-squared' );
var rateval12 = require( './rational_p12q12.js' );
var rateval24 = require( './rational_p24q24.js' );
var rateval48 = require( './rational_p48q48.js' );
var rateval816 = require( './rational_p816q816.js' );
var rateval16INF = require( './rational_p16infq16inf.js' );
// VARIABLES //
var YOFFSET24 = 3.558437347412109375;
// MAIN //
/**
* Evaluates the trigamma function.
*
* @param {number} x - input value
* @returns {number} function value
*
* @example
* var v = trigamma( -2.5 );
* // returns ~9.539
*
* @example
* var v = trigamma( 1.0 );
* // returns ~1.645
*
* @example
* var v = trigamma( 10.0 );
* // returns ~0.105
*
* @example
* var v = trigamma( NaN );
* // returns NaN
*
* @example
* var v = trigamma( -1.0 );
* // returns NaN
*/
function trigamma( x ) {
var result;
var s;
var y;
var z;
result = 0.0;
// Check for negative arguments and use reflection:
if ( x <= 0 ) {
if ( floor( x ) === x ) {
return NaN;
}
s = sinpi( x );
z = 1.0 - x;
return -trigamma( z ) + ( PI_SQUARED / ( s*s ) );
}
if ( x < 1.0 ) {
result = 1.0 / ( x*x );
x += 1.0;
}
if ( x <= 2.0 ) {
result += ( 2.0+rateval12( x ) ) / ( x*x );
}
else if ( x <= 4.0 ) {
result += ( YOFFSET24+rateval24( x ) ) / ( x*x );
}
else if ( x <= 8.0 ) {
y = 1.0 / x;
result += ( 1.0+rateval48( y ) ) / x;
}
else if ( x <= 16.0 ) {
y = 1.0 / x;
result += ( 1.0+rateval816( y ) ) / x;
}
else {
y = 1.0 / x;
result += ( 1.0+rateval16INF( y ) ) / x;
}
return result;
}
// EXPORTS //
module.exports = trigamma;
|