# @stdlib/math-base-special-ahavercos

0.2.2 • Public • Published

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# Archavercosine

Compute the inverse half-value versed cosine.

The inverse half-value versed cosine is defined as

## Installation

npm install @stdlib/math-base-special-ahavercos

## Usage

var ahavercos = require( '@stdlib/math-base-special-ahavercos' );

#### ahavercos( x )

Computes the inverse half-value versed cosine.

var v = ahavercos( 0.0 );
// returns ~3.1416

v = ahavercos( 1.0 );
// returns 0.0

v = ahavercos( 0.5 );
// returns ~1.5708

If x < 0, x > 1, or x is NaN, the function returns NaN.

var v = ahavercos( 1.5 );
// returns NaN

v = ahavercos( -3.14 );
// returns NaN

v = ahavercos( NaN );
// returns NaN

## Examples

var linspace = require( '@stdlib/array-base-linspace' );
var ahavercos = require( '@stdlib/math-base-special-ahavercos' );

var x = linspace( 0.0, 1.0, 100 );

var i;
for ( i = 0; i < x.length; i++ ) {
console.log( ahavercos( x[ i ] ) );
}

## C APIs

### Usage

#include "stdlib/math/base/special/ahavercos.h"

#### stdlib_base_ahavercos( x )

Compute the inverse half-value versed cosine of a double-precision floating-point number (in radians).

double out = stdlib_base_ahavercos( 0.0 );
// returns ~3.1416

If x < 0, x > 1, or x is NaN, the function returns NaN.

double out = stdlib_base_ahavercos( -3.14 );
// returns NaN

The function accepts the following arguments:

• x: [in] double input value.
double stdlib_base_ahavercos( const double x );

### Examples

#include "stdlib/math/base/special/ahavercos.h"
#include <stdio.h>

int main( void ) {
const double x[] = { -2.0, -1.6, -1.2, -0.8, -0.4, 0.4, 0.8, 1.2, 1.6, 2.0 };

double v;
int i;
for ( i = 0; i < 10; i++ ) {
v = stdlib_base_ahavercos( x[ i ] );
printf( "ahavercos(%lf) = %lf\n", x[ i ], v );
}
}

## 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.

## Package Sidebar

### Install

npm i @stdlib/math-base-special-ahavercos

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