All files / math/base/special/cosc/lib main.js

100% Statements 89/89
100% Branches 8/8
100% Functions 1/1
100% Lines 89/89

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 901x 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 7019x 7019x 1x 1x 7019x 2x 2x 7019x 2x 2x 7014x 7019x 1x 1x 1x 1x 1x  
/**
* @license Apache-2.0
*
* Copyright (c) 2024 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 sinpi = require( '@stdlib/math/base/special/sinpi' );
var cospi =require('@stdlib/math/base/special/cospi');
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var isInfinite = require( '@stdlib/math/base/assert/is-infinite' );
var PI = require( '@stdlib/constants/float64/pi' );
 
 
// MAIN //
 
/**
* Computes the normalized derivative of cardinal sine of a number.
*
* ## Method
*
* For \\( x \neq 0 \\), the normalized derivative of cardinal sine is calculated as
*
* ```tex
* \operatorname{cosc}(x) = \frac{{\operatorname{cos}(\pi x)}-\frac{\operatorname{sin}(\pi x)}{\pi x}}{x}.
* ```
*
* ## Special Cases
*
* ```tex
* \begin{align*}
* \operatorname{cosc}(0) &= 0 & \\
* \operatorname{cosc}(\infty) &= 0 & \\
* \operatorname{cosc}(-\infty) &= 0 & \\
* \operatorname{cosc}(\mathrm{NaN}) &= \mathrm{NaN}
* \end{align*}
* ```
*
* @param {number} x - input value
* @returns {number} derivative of cardinal sine
*
* @example
* var v = cosc( 0.5 );
* // returns ~-1.273
*
* @example
* var v = cosc( -1.2 );
* // returns ~0.544
*
* @example
* var v = cosc( 0.0 );
* // returns 0.0
*
* @example
* var v = cosc( NaN );
* // returns NaN
*/
function cosc( x ) {
	if ( isnan( x ) ) {
		return NaN;
	}
	if ( isInfinite( x ) ) {
		return 0.0;
	}
	if ( x === 0.0 ) {
		return 0.0;
	}
    return ( cospi( x ) - ( sinpi( x ) / ( PI * x ) ) ) / x ;
}
 
 
// EXPORTS //
 
module.exports = cosc;