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 | 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.
*/
'use strict';
// MODULES //
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var isInfinite = require( '@stdlib/math/base/assert/is-infinite' );
var cos = require( '@stdlib/math/base/special/cos' );
var sin = require( '@stdlib/math/base/special/sin' );
var abs = require( '@stdlib/math/base/special/abs' );
var copysign = require( '@stdlib/math/base/special/copysign' );
var PI = require( '@stdlib/constants/float64/pi' );
// MAIN //
/**
* Computes the value of `sin(πx)`.
*
* ## Notes
*
* - The function computes `sin(πx)` more accurately than the obvious approach, especially for large `x`.
*
* @param {number} x - input value
* @returns {number} function value
*
* @example
* var y = sinpi( 0.0 );
* // returns 0.0
*
* @example
* var y = sinpi( 0.5 );
* // returns 1.0
*
* @example
* var y = sinpi( 0.9 );
* // returns ~0.309
*
* @example
* var y = sinpi( NaN );
* // returns NaN
*/
function sinpi( x ) {
var ar;
var r;
if ( isnan( x ) ) {
return NaN;
}
if ( isInfinite( x ) ) {
return NaN;
}
// Argument reduction (reduce to [0,2))...
r = x % 2.0; // sign preserving
ar = abs( r );
// If `x` is an integer, the mod is an integer...
if ( ar === 0.0 || ar === 1.0 ) {
return copysign( 0.0, r );
}
if ( ar < 0.25 ) {
return sin( PI*r );
}
// In each of the following, we further reduce to [-π/4,π/4)...
if ( ar < 0.75 ) {
ar = 0.5 - ar;
return copysign( cos( PI*ar ), r );
}
if ( ar < 1.25 ) {
r = copysign( 1.0, r ) - r;
return sin( PI*r );
}
if ( ar < 1.75 ) {
ar -= 1.5;
return -copysign( cos( PI*ar ), r );
}
r -= copysign( 2.0, r );
return sin( PI*r );
}
// EXPORTS //
module.exports = sinpi;
|