@stdlib/math-base-special-kernel-tan
v0.2.4TypeScript
Compute the tangent of a double-precision floating-point number on [-π/4, π/4].
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Published by The Stdlib Authors
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kernelTan
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> Compute the [tangent][tangent] of a double-precision floating-point number on [-π/4, π/4].
Installation
``bash`
npm install @stdlib/math-base-special-kernel-tan
Usage
`javascript`
var kernelTan = require( '@stdlib/math-base-special-kernel-tan' );
#### kernelTan( x, y, k )
Computes the [tangent][tangent] of a double-precision floating-point number on [-π/4, π/4].
`javascript
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.
`javascript`
var out = kernelTan( 3.141592653589793/4.0, 0.0, -1 );
// returns ~-1.0
If either x or y is NaN, the function returns NaN.
`javascript
var out = kernelTan( NaN, 0.0, 1 );
// returns NaN
out = kernelTan( 3.0, NaN, 1 );
// returns NaN
out = kernelTan( NaN, NaN, 1 );
// returns NaN
`
Notes
- For increased accuracy, the number for which the [tangent][tangent] should be evaluated can be supplied as a [double-double number][double-double-arithmetic] (i.e., a non-evaluated sum of two [double-precision floating-point numbers][ieee754] x and y).
- As components of a [double-double number][double-double-arithmetic], the two [double-precision floating-point numbers][ieee754] x and y must satisfy
where ulp stands for [units in the last place][ulp].
Examples
`javascript
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 ) );
}
`
*
C APIs
$3
`c`
#include "stdlib/math/base/special/kernel_tan.h"
#### stdlib_base_kernel_tan( x, y, k )
Computes the [tangent][tangent] of a double-precision floating-point number on [-π/4, π/4].
`c
double out = stdlib_base_kernel_tan( 3.141592653589793/4.0, 0.0, 1 );
// returns ~1.0
out = stdlib_base_kernel_tan( 3.141592653589793/6.0, 0.0, 1 );
// returns ~0.577
`
The function accepts the following arguments:
- x: [in] double input value (in radians, assumed to be bounded by ~pi/4 in magnitude).[in] double
- y: tail of x.[in] int32_t
- k: indicates whether tan(x+y) (if k = 1) or -1/tan(x+y) (if k = -1) is returned.
`c`
double stdlib_base_kernel_tan( const double x, const double y, const int32_t k );
$3
- For increased accuracy, the number for which the [tangent][tangent] should be evaluated can be supplied as a [double-double number][double-double-arithmetic] (i.e., a non-evaluated sum of two [double-precision floating-point numbers][ieee754] x and y).
$3
`c
#include "stdlib/math/base/special/kernel_tan.h"
#include
int main( void ) {
const double x[] = { -0.7853981633974483, -0.6108652381980153, -0.4363323129985824, -0.26179938779914946, -0.08726646259971649, 0.08726646259971649, 0.26179938779914935, 0.43633231299858233, 0.6108652381980153, 0.7853981633974483 };
double out;
int i;
for ( i = 0; i < 10; i++ ) {
out = stdlib_base_kernel_tan( x[ i ], 0.0, 1 );
printf( "tan(%lf) = %lf\n", x[ i ], out );
}
}
`
*
See Also
- [@stdlib/math-base/special/kernel-cos][@stdlib/math/base/special/kernel-cos]: compute the cosine of a double-precision floating-point number on \[-π/4, π/4].
- [@stdlib/math-base/special/kernel-sin][@stdlib/math/base/special/kernel-sin]: compute the sine of a double-precision floating-point number on \[-π/4, π/4].
- [@stdlib/math-base/special/tan][@stdlib/math/base/special/tan]: evaluate the tangent of a number.
*
Notice
This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].
#### Community
[![Chat][chat-image]][chat-url]
---
Copyright
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/math-base-special-kernel-tan.svg
[npm-url]: https://npmjs.org/package/@stdlib/math-base-special-kernel-tan
[test-image]: https://github.com/stdlib-js/math-base-special-kernel-tan/actions/workflows/test.yml/badge.svg?branch=v0.2.4
[test-url]: https://github.com/stdlib-js/math-base-special-kernel-tan/actions/workflows/test.yml?query=branch:v0.2.4
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/math-base-special-kernel-tan/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/math-base-special-kernel-tan?branch=main
[chat-image]: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg
[chat-url]: https://stdlib.zulipchat.com
[stdlib]: https://github.com/stdlib-js/stdlib
[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors
[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules
[deno-url]: https://github.com/stdlib-js/math-base-special-kernel-tan/tree/deno
[deno-readme]: https://github.com/stdlib-js/math-base-special-kernel-tan/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/math-base-special-kernel-tan/tree/umd
[umd-readme]: https://github.com/stdlib-js/math-base-special-kernel-tan/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/math-base-special-kernel-tan/tree/esm
[esm-readme]: https://github.com/stdlib-js/math-base-special-kernel-tan/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/math-base-special-kernel-tan/blob/main/branches.md
[tangent]: https://en.wikipedia.org/wiki/Tangent
[double-double-arithmetic]: https://en.wikipedia.org/wiki/Quadruple-precision_floating-point_format#Double-double_arithmetic
[ieee754]: https://en.wikipedia.org/wiki/IEEE_floating_point
[ulp]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[@stdlib/math/base/special/kernel-cos]: https://www.npmjs.com/package/@stdlib/math-base-special-kernel-cos
[@stdlib/math/base/special/kernel-sin]: https://www.npmjs.com/package/@stdlib/math-base-special-kernel-sin
[@stdlib/math/base/special/tan]: https://www.npmjs.com/package/@stdlib/math-base-special-tan