@stdlib/strided
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Strided.
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<!-- lint disable maximum-heading-length -->
# dmskmap2
> Apply a binary function to double-precision floating-point strided input arrays according to a strided mask array and assign results to a double-precision floating-point strided output array.
<section class="intro">
</section>
<!-- /.intro -->
<section class="usage">
## Usage
```javascript
var dmskmap2 = require( '@stdlib/strided/base/dmskmap2' );
```
#### dmskmap2( N, x, strideX, y, strideY, mask, strideMask, z, strideZ, fcn )
Applies a binary function to double-precision floating-point strided input arrays according to a strided mask array and assigns results to a double-precision floating-point strided output array.
```javascript
var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );
var add = require( '@stdlib/math/base/ops/add' );
var x = new Float64Array( [ -2.0, 1.0, -3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );
var y = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var z = new Float64Array( x.length );
var m = new Uint8Array( [ 0, 0, 1, 0, 0, 1, 1, 0 ] );
dmskmap2( x.length, x, 1, y, 1, m, 1, z, 1, add );
// z => <Float64Array>[ -1.0, 3.0, 0.0, -1.0, 9.0, 0.0, 0.0, 5.0 ]
```
The function accepts the following arguments:
- **N**: number of indexed elements.
- **x**: input [`Float64Array`][@stdlib/array/float64].
- **strideX**: index increment for `x`.
- **y**: input [`Float64Array`][@stdlib/array/float64].
- **strideY**: index increment for `y`.
- **mask**: mask [`Uint8Array`][@stdlib/array/uint8].
- **strideMask**: index increment for `mask`.
- **z**: output [`Float64Array`][@stdlib/array/float64].
- **strideZ**: index increment for `z`.
- **fcn**: function to apply.
The `N` and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to index every other value in `x` and to index the first `N` elements of `y` in reverse order,
```javascript
var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );
var add = require( '@stdlib/math/base/ops/add' );
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y = new Float64Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ] );
var z = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 0, 1 ] );
dmskmap2( 3, x, 2, y, -1, m, 2, z, 1, add );
// z => <Float64Array>[ 1.0, 0.0, -4.0, 0.0, 0.0, 0.0 ]
```
Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][@stdlib/array/float64] views.
```javascript
var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );
var add = require( '@stdlib/math/base/ops/add' );
// Initial arrays...
var x0 = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y0 = new Float64Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ] );
var z0 = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
var m0 = new Uint8Array( [ 0, 0, 1, 0, 0, 1 ] );
// Create offset views...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
var z1 = new Float64Array( z0.buffer, z0.BYTES_PER_ELEMENT*2 ); // start at 3rd element
var m1 = new Uint8Array( m0.buffer, m0.BYTES_PER_ELEMENT*3 ); // start at 4th element
dmskmap2( 3, x1, -2, y1, 1, m1, 1, z1, 1, add );
// z0 => <Float64Array>[ 0.0, 0.0, -4.0, -1.0, 0.0, 0.0 ]
```
#### dmskmap2.ndarray( N, x, strideX, offsetX, y, strideY, offsetY, mask, strideMask, offsetMask, z, strideZ, offsetZ, fcn )
Applies a binary function to double-precision floating-point strided input arrays according to a strided mask array and assigns results to a double-precision floating-point strided output array using alternative indexing semantics.
```javascript
var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );
var add = require( '@stdlib/math/base/ops/add' );
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0 ] );
var y = new Float64Array( [ 1.0, 1.0, 2.0, 2.0, 3.0 ] );
var z = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 0 ] );
dmskmap2.ndarray( x.length, x, 1, 0, y, 1, 0, m, 1, 0, z, 1, 0, add );
// z => <Float64Array>[ 0.0, -1.0, 0.0, -2.0, -2.0 ]
```
The function accepts the following additional arguments:
- **offsetX**: starting index for `x`.
- **offsetY**: starting index for `y`.
- **offsetMask**: starting index for `mask`.
- **offsetZ**: starting index for `z`.
While [`typed array`][@stdlib/array/float64] views mandate a view offset based on the underlying `buffer`, the offset parameters support indexing semantics based on starting indices. For example, to index every other value in `x` starting from the second value and to index the last `N` elements in `y` in reverse order,
```javascript
var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );
var add = require( '@stdlib/math/base/ops/add' );
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y = new Float64Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ] );
var z = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 0, 1 ] );
dmskmap2.ndarray( 3, x, 2, 1, y, -1, y.length-1, m, 2, 1, z, 1, 0, add );
// z => <Float64Array>[ 1.0, -1.0, 0.0, 0.0, 0.0, 0.0 ]
```
</section>
<!-- /.usage -->
<section class="notes">
</section>
<!-- /.notes -->
<section class="examples">
## Examples
<!-- eslint no-undef: "error" -->
```javascript
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
var bernoulli = require( '@stdlib/random/base/bernoulli' ).factory;
var Float64Array = require( '@stdlib/array/float64' );
var filledarrayBy = require( '@stdlib/array/filled-by' );
var add = require( '@stdlib/math/base/ops/add' );
var dmskmap2 = require( '@stdlib/strided/base/dmskmap2' );
var x = filledarrayBy( 10, 'float64', discreteUniform( -100, 100 ) );
console.log( x );
var y = filledarrayBy( x.length, 'float64', discreteUniform( -100, 100 ) );
console.log( y );
var m = filledarrayBy( x.length, 'uint8', bernoulli( 0.2 ) );
console.log( m );
var z = new Float64Array( x.length );
console.log( z );
dmskmap2.ndarray( x.length, x, 1, 0, y, -1, y.length-1, m, 1, 0, z, 1, 0, add );
console.log( z );
```
</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/strided/base/dmskmap2.h"
```
#### stdlib_strided_dmskmap2( N, \*X, strideX, \*Y, strideY, \*Mask, strideMask, \*Z, strideZ, fcn )
Applies a binary function to double-precision floating-point strided input arrays according to a strided mask array and assigns results to a double-precision floating-point strided output array.
```c
#include <stdint.h>
static double add( const double x, const double y ) {
return x + y;
}
double X[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 };
double Y[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 };
double Z[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
uint8_t M[] = { 0, 0, 1, 0, 0, 1 };
int64_t N = 6;
stdlib_strided_dmskmap2( N, X, 1, Y, 1, M, 1, Z, 1, add );
```
The function accepts the following arguments:
- **N**: `[in] int64_t` number of indexed elements.
- **X**: `[in] double*` input array.
- **strideX** `[in] int64_t` index increment for `X`.
- **Y**: `[int] double*` input array.
- **strideY**: `[in] int64_t` index increment for `Y`.
- **Mask**: `[in] uint8_t*` mask array.
- **strideMask**: `[in] int64_t` index increment for `Mask`.
- **Z**: `[out] double*` output array.
- **strideZ**: `[in] int64_t` index increment for `Z`.
- **fcn**: `[in] double (*fcn)( double, double )` binary function to apply.
```c
void stdlib_strided_dmskmap2( const int64_t N, const double *X, const int64_t strideX, const double *Y, const int64_t strideY, const uint8_t *Mask, const int64_t strideMask, double *Z, const int64_t strideZ, double (*fcn)( double, double ) );
```
</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/strided/base/dmskmap2.h"
#include <stdint.h>
#include <stdio.h>
#include <inttypes.h>
// Define a callback:
static double add( const double x, const double y ) {
return x + y;
}
int main( void ) {
// Create input strided arrays:
double X[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 };
double Y[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 };
// Create a mask strided array:
uint8_t M[] = { 0, 0, 1, 0, 0, 1 };
// Create an output strided array:
double Z[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
// Specify the number of elements:
int64_t N = 6;
// Define the strides:
int64_t strideX = 1;
int64_t strideY = -1;
int64_t strideZ = 1;
int64_t strideM = 1;
// Apply the callback:
stdlib_strided_dmskmap2( N, X, strideX, Y, strideY, M, strideM, Z, strideZ, add );
// Print the results:
for ( int64_t i = 0; i < N; i++ ) {
printf( "Z[ %"PRId64" ] = %lf\n", i, Z[ i ] );
}
}
```
</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/strided/base/dmap2`][@stdlib/strided/base/dmap2]</span><span class="delimiter">: </span><span class="description">apply a binary function to double-precision floating-point strided input arrays and assign results to a double-precision floating-point strided output array.</span>
- <span class="package-name">[`@stdlib/strided/base/dmskmap`][@stdlib/strided/base/dmskmap]</span><span class="delimiter">: </span><span class="description">apply a unary function to a double-precision floating-point strided input array according to a strided mask array and assign results to a double-precision floating-point strided output array.</span>
- <span class="package-name">[`@stdlib/strided/base/smskmap2`][@stdlib/strided/base/smskmap2]</span><span class="delimiter">: </span><span class="description">apply a binary function to single-precision floating-point strided input arrays according to a strided mask array and assign results to a single-precision floating-point strided output array.</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/array/float64]: https://www.npmjs.com/package/@stdlib/array-float64
[@stdlib/array/uint8]: https://www.npmjs.com/package/@stdlib/array-uint8
<!-- <related-links> -->
[@stdlib/strided/base/dmap2]: https://github.com/stdlib-js/strided/tree/main/base/dmap2
[@stdlib/strided/base/dmskmap]: https://github.com/stdlib-js/strided/tree/main/base/dmskmap
[@stdlib/strided/base/smskmap2]: https://github.com/stdlib-js/strided/tree/main/base/smskmap2
<!-- </related-links> -->
</section>
<!-- /.links -->