# npm

## @stdlib/math-base-special-kernel-tan 0.0.6 • Public • Published

# Kernel Tangent

Compute the tangent of a number on `[-π/4, π/4]`.

## Installation

`npm install @stdlib/math-base-special-kernel-tan`

## Usage

`var kernelTan = require( '@stdlib/math-base-special-kernel-tan' );`

#### kernelTan( x, y, k )

Computes the tangent of a `number` on `[-π/4, π/4]`. For increased accuracy, the number for which the tangent should be evaluated can be supplied as a double-double number (i.e., a non-evaluated sum of two double-precision floating-point numbers `x` and `y`).

```var out = kernelTan( 3.141592653589793/4.0, 0.0, 1 );
// returns ~1.0

out = kernelTan( 3.141592653589793/6.0, 0.0, 1 );
// returns ~0.577

out = kernelTan( 0.664, 5.288e-17, 1 );
// returns ~0.783```

If `k = 1`, the function returns `tan(x+y)`. To return the negative inverse `-1/tan(x+y)`, set `k = -1`.

```var out = kernelTan( 3.141592653589793/4.0, 0.0, -1 );
// returns ~-1.0```

If either `x` or `y` is `NaN`, the function returns `NaN`.

```var out = kernelTan( NaN, 0.0, 1 );
// returns NaN

out = kernelTan( 3.0, NaN, 1 );
// returns NaN

out = kernelTan( NaN, NaN, 1 );
// returns NaN```

## Examples

```var linspace = require( '@stdlib/array-base-linspace' );
var binomial = require( '@stdlib/random-base-binomial' ).factory;
var PI = require( '@stdlib/constants-float64-pi' );
var kernelTan = require( '@stdlib/math-base-special-kernel-tan' );

var x = linspace( -PI/4.0, PI/4.0, 100 );
var rbinom = binomial( 1, 0.5 );

var descr;
var i;
var k;

for ( i = 0; i < x.length; i++ ) {
k = rbinom();
descr = ( k === 1 ) ? 'tan(%d) = %d' : '-1/tan(%d) = %d';
console.log( descr, x[ i ], kernelTan( x[ i ], 0.0, k ) );
}```

## 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.

#### Community ## Keywords

### Install

`npm i @stdlib/math-base-special-kernel-tan`

stdlib.io

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0.0.6