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# sincospi

> Simultaneously compute the [sine][@stdlib/math/base/special/sin] and [cosine][@stdlib/math/base/special/cos] of a number times [π][@stdlib/constants/float64/pi].

<section class="usage">

## Usage

```javascript
var sincospi = require( '@stdlib/math/base/special/sincospi' );
```

#### sincospi( x )

Simultaneously computes the [sine][@stdlib/math/base/special/sin] and [cosine][@stdlib/math/base/special/cos] of a `number` times [π][@stdlib/constants/float64/pi] more accurately than `sincos(pi*x)`, especially for large `x`.

```javascript
var v = sincospi( 0.0 );
// returns [ 0.0, 1.0 ]

v = sincospi( 0.5 );
// returns [ 1.0, 0.0 ]

v = sincospi( 0.1 );
// returns [ ~0.309, ~0.951 ]

v = sincospi( NaN );
// returns [ NaN, NaN ]
```

#### sincospi( x, out, stride, offset )

Simultaneously computes the [sine][@stdlib/math/base/special/sin] and [cosine][@stdlib/math/base/special/cos] of a `number` times [π][@stdlib/constants/float64/pi] more accurately than `sincos(pi*x)`, especially for large `x`, and assigns results to a provided output array.

```javascript
var Float64Array = require( '@stdlib/array/float64' );

var out = new Float64Array( 2 );

var v = sincospi.assign( 0.0, out, 1, 0 );
// returns <Float64Array>[ 0.0, 1.0 ]

var bool = ( v === out );
// returns true
```

</section>

<!-- /.usage -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var linspace = require( '@stdlib/array/base/linspace' );
var sincospi = require( '@stdlib/math/base/special/sincospi' );

var x = linspace( 0.0, 2.0, 101 );

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

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- C usage documentation. -->

<section class="usage">

### Usage

```c
#include "stdlib/math/base/special/sincospi.h"
```

#### stdlib_base_sincospi( x, &sine, &cosine )

Simultaneously computes the [sine][@stdlib/math/base/special/sin] and [cosine][@stdlib/math/base/special/cos] of a `number` times [π][@stdlib/constants/float64/pi] more accurately than `sincos(pi*x)`, especially for large `x`.

```c
double cosine;
double sine;

stdlib_base_sincospi( 4.0, &sine, &cosine );
```

The function accepts the following arguments:

-   **x**:      `[in] double` input value.
-   **sine**:   `[out] double*` destination for the sine.
-   **cosine**: `[out] double*` destination for the cosine.

```c
void stdlib_base_sincospi( const double x, double *sine, double *cosine );
```

</section>

<!-- /.usage -->

<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- C API usage examples. -->

<section class="examples">

### Examples

```c
#include "stdlib/math/base/special/sincospi.h"
#include <stdio.h>

int main( void ) {
    const double x[] = { 0.0, 1.57, 3.14, 6.28 };

    double cosine;
    double sine;
    int i;
    for ( i = 0; i < 4; i++ ) {
        stdlib_base_sincospi( x[ i ], &sine, &cosine );
        printf( "x: %lf => sine: %lf, cosine: %lf\n", x[ i ], sine, cosine );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/math/base/special/cospi`][@stdlib/math/base/special/cospi]</span><span class="delimiter">: </span><span class="description">compute cos(πx).</span>
-   <span class="package-name">[`@stdlib/math/base/special/sincos`][@stdlib/math/base/special/sincos]</span><span class="delimiter">: </span><span class="description">simultaneously compute the sine and cosine of an angle measured in radians.</span>
-   <span class="package-name">[`@stdlib/math/base/special/sinpi`][@stdlib/math/base/special/sinpi]</span><span class="delimiter">: </span><span class="description">compute sin(πx).</span>

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

[@stdlib/math/base/special/sin]: https://github.com/stdlib-js/math/tree/main/base/special/sin

[@stdlib/math/base/special/cos]: https://github.com/stdlib-js/math/tree/main/base/special/cos

[@stdlib/constants/float64/pi]: https://www.npmjs.com/package/@stdlib/constants-float64-pi

<!-- <related-links> -->

[@stdlib/math/base/special/cospi]: https://github.com/stdlib-js/math/tree/main/base/special/cospi

[@stdlib/math/base/special/sincos]: https://github.com/stdlib-js/math/tree/main/base/special/sincos

[@stdlib/math/base/special/sinpi]: https://github.com/stdlib-js/math/tree/main/base/special/sinpi

<!-- </related-links> -->

</section>

<!-- /.links -->
