<!-- @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. --> # rempio2 > Compute `x - nπ/2 = r`. <section class="usage"> ## Usage ```javascript var rempio2 = require( '@stdlib/math/base/special/rempio2' ); ``` #### rempio2( x, y ) Computes `x - nπ/2 = r`. The function returns `n` and stores the remainder `r` as two numbers in `y`, such that `y[0]+y[1] = r`. ```javascript var y = [ 0.0, 0.0 ]; var n = rempio2( 128.0, y ); // returns 81 var y1 = y[ 0 ]; // returns ~0.765 var y2 = y[ 1 ]; // returns ~3.618e-17 ``` When `x` is `NaN` or infinite, the function returns zero and sets the elements of `y` to `NaN`. ```javascript var y = [ 0.0, 0.0 ]; var n = rempio2( NaN, y ); // returns 0 var y1 = y[ 0 ]; // returns NaN var y2 = y[ 1 ]; // returns NaN y = [ 0.0, 0.0 ]; n = rempio2( Infinity, y ); // returns 0 y1 = y[ 0 ]; // returns NaN y2 = y[ 1 ]; // returns NaN ``` </section> <!-- /.usage --> <!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> <section class="notes"> ## Notes - For input values larger than `2^20*π/2` in magnitude, the function **only** returns the last three binary digits of `n` and not the full result. </section> <!-- /.notes --> <section class="examples"> ## Examples <!-- eslint no-undef: "error" --> ```javascript var linspace = require( '@stdlib/array/linspace' ); var rempio2 = require( '@stdlib/math/base/special/rempio2' ); var x = linspace( 0.0, 100.0, 100 ); var y = [ 0.0, 0.0 ]; var n; var i; for ( i = 0; i < x.length; i++ ) { n = rempio2( x[ i ], y ); console.log( '%d - %dπ/2 = %d + %d', x[ i ], n, y[ 0 ], y[ 1 ] ); } ``` </section> <!-- /.examples --> <section class="links"> </section> <!-- /.links -->