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# npm

## @stdlib/math-base-special-rempio2

0.0.5 • Public • Published

# rempio2

Compute `x - nπ/2 = r`.

## Installation

`npm install @stdlib/math-base-special-rempio2`

## Usage

`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`.

```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`.

```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```

## 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.

## Examples

```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 ] );
}```

## Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

## Keywords

### Install

`npm i @stdlib/math-base-special-rempio2`

### Repository

github.com/stdlib-js/math-base-special-rempio2

stdlib.io

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0.0.5

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