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136 changes: 127 additions & 9 deletions lib/node_modules/@stdlib/blas/ext/base/drev/README.md
Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ limitations under the License.
var drev = require( '@stdlib/blas/ext/base/drev' );
```

#### drev( N, x, stride )
#### drev( N, x, strideX )

Reverses a double-precision floating-point strided array `x` in-place.

Expand All @@ -47,9 +47,9 @@ The function has the following parameters:

- **N**: number of indexed elements.
- **x**: input [`Float64Array`][@stdlib/array/float64].
- **stride**: index increment.
- **strideX**: stride length.

The `N` and stride parameters determine which elements in the strided array are accessed at runtime. For example, to reverse every other element
The `N` and stride parameters determine which elements in the strided array are accessed at runtime. For example, to reverse every other element:

```javascript
var Float64Array = require( '@stdlib/array/float64' );
Expand All @@ -76,7 +76,7 @@ drev( 3, x1, 2 );
// x0 => <Float64Array>[ 1.0, -6.0, 3.0, -4.0, 5.0, -2.0 ]
```

#### drev.ndarray( N, x, stride, offset )
#### drev.ndarray( N, x, strideX, offsetX )

Reverses a double-precision floating-point strided array `x` in-place using alternative indexing semantics.

Expand All @@ -91,9 +91,9 @@ drev.ndarray( x.length, x, 1, 0 );

The function has the following additional parameters:

- **offset**: starting index.
- **offsetX**: starting index.

While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying `buffer`, the `offset` parameter supports indexing semantics based on a starting index. For example, to access only the last three elements of the strided array
While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index. For example, to access only the last three elements of the strided array:

```javascript
var Float64Array = require( '@stdlib/array/float64' );
Expand Down Expand Up @@ -126,11 +126,12 @@ drev.ndarray( 3, x, 1, x.length-3 );
<!-- eslint no-undef: "error" -->

```javascript
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
var filledarrayBy = require( '@stdlib/array/filled-by' );
var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var drev = require( '@stdlib/blas/ext/base/drev' );

var x = filledarrayBy( 10, 'float64', discreteUniform( -100.0, 100.0 ) );
var x = discreteUniform( 10, -100, 100, {
'dtype': 'float64'
});
console.log( x );

drev( x.length, x, 1 );
Expand All @@ -141,6 +142,123 @@ console.log( x );

<!-- /.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/blas/ext/base/drev.h"
```

#### stdlib_strided_drev( N, \*X, strideX )

Reverses a double-precision floating-point strided array `X` in-place.

```c
double x[] = { 1.0, 2.0, 3.0, 4.0 };

stdlib_strided_drev( 4, x, 1 );
```

The function accepts the following arguments:

- **N**: `[in] CBLAS_INT` number of indexed elements.
- **X**: `[in] double*` input array.
- **strideX**: `[in] CBLAS_INT` stride length for `X`.

```c
double stdlib_strided_drev( const CBLAS_INT N, const double *X, const CBLAS_INT strideX );
```

#### stdlib_strided_drev_ndarray( N, \*X, strideX, offsetX )

Reverses a double-precision floating-point strided array `X` in-place using alternative indexing semantics.

```c
double x[] = { 1.0, 2.0, 3.0, 4.0 };

stdlib_strided_drev_ndarray( 4, x, 1, 0 );
```

The function accepts the following arguments:

- **N**: `[in] CBLAS_INT` number of indexed elements.
- **X**: `[in] double*` input array.
- **strideX**: `[in] CBLAS_INT` stride length for `X`.
- **offsetX**: `[in] CBLAS_INT` starting index for `X`.

```c
void stdlib_strided_drev_ndarray( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );
```

</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/blas/ext/base/drev.h"
#include <stdio.h>

int main( void ) {
// Create a strided array:
double x[] = { 1.0, -2.0, 3.0, -4.0, 5.0, -6.0, 7.0, -8.0 };

// Specify the number of elements:
const int N = 8;

// Specify a stride:
const int strideX = 1;

// Reverse the array:
stdlib_strided_drev( N, x, strideX );

// Print the result:
for ( int i = 0; i < 8; i++ ) {
printf( "x[ %i ] = %lf\n", i, x[ i ] );
}
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

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

<section class="related">
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,7 @@
// MODULES //

var bench = require( '@stdlib/bench' );
var uniform = require( '@stdlib/random/base/uniform' ).factory;
var filledarrayBy = require( '@stdlib/array/filled-by' );
var uniform = require( '@stdlib/random/array/uniform' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var pow = require( '@stdlib/math/base/special/pow' );
var pkg = require( './../package.json' ).name;
Expand All @@ -31,7 +30,9 @@ var drev = require( './../lib/drev.js' );

// VARIABLES //

var rand = uniform( -10.0, 10.0 );
var options = {
'dtype': 'float64'
};


// FUNCTIONS //
Expand All @@ -44,7 +45,7 @@ var rand = uniform( -10.0, 10.0 );
* @returns {Function} benchmark function
*/
function createBenchmark( len ) {
var x = filledarrayBy( len, 'float64', rand );
var x = uniform( len, -10.0, 10.0, options );
return benchmark;

function benchmark( b ) {
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -22,8 +22,7 @@

var resolve = require( 'path' ).resolve;
var bench = require( '@stdlib/bench' );
var uniform = require( '@stdlib/random/base/uniform' ).factory;
var filledarrayBy = require( '@stdlib/array/filled-by' );
var uniform = require( '@stdlib/random/array/uniform' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var pow = require( '@stdlib/math/base/special/pow' );
var tryRequire = require( '@stdlib/utils/try-require' );
Expand All @@ -36,7 +35,9 @@ var drev = tryRequire( resolve( __dirname, './../lib/drev.native.js' ) );
var opts = {
'skip': ( drev instanceof Error )
};
var rand = uniform( -10.0, 10.0 );
var options = {
'dtype': 'float64'
};


// FUNCTIONS //
Expand All @@ -49,7 +50,7 @@ var rand = uniform( -10.0, 10.0 );
* @returns {Function} benchmark function
*/
function createBenchmark( len ) {
var x = filledarrayBy( len, 'float64', rand );
var x = uniform( len, -10.0, 10.0, options );
return benchmark;

function benchmark( b ) {
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,7 @@
// MODULES //

var bench = require( '@stdlib/bench' );
var uniform = require( '@stdlib/random/base/uniform' ).factory;
var filledarrayBy = require( '@stdlib/array/filled-by' );
var uniform = require( '@stdlib/random/array/uniform' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var pow = require( '@stdlib/math/base/special/pow' );
var pkg = require( './../package.json' ).name;
Expand All @@ -31,7 +30,9 @@ var drev = require( './../lib/ndarray.js' );

// VARIABLES //

var rand = uniform( -10.0, 10.0 );
var options = {
'dtype': 'float64'
};


// FUNCTIONS //
Expand All @@ -44,7 +45,7 @@ var rand = uniform( -10.0, 10.0 );
* @returns {Function} benchmark function
*/
function createBenchmark( len ) {
var x = filledarrayBy( len, 'float64', rand );
var x = uniform( len, -10.0, 10.0, options );
return benchmark;

function benchmark( b ) {
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -22,8 +22,7 @@

var resolve = require( 'path' ).resolve;
var bench = require( '@stdlib/bench' );
var uniform = require( '@stdlib/random/base/uniform' ).factory;
var filledarrayBy = require( '@stdlib/array/filled-by' );
var uniform = require( '@stdlib/random/array/uniform' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var pow = require( '@stdlib/math/base/special/pow' );
var tryRequire = require( '@stdlib/utils/try-require' );
Expand All @@ -36,7 +35,9 @@ var drev = tryRequire( resolve( __dirname, './../lib/ndarray.native.js' ) );
var opts = {
'skip': ( drev instanceof Error )
};
var rand = uniform( -10.0, 10.0 );
var options = {
'dtype': 'float64'
};


// FUNCTIONS //
Expand All @@ -49,7 +50,7 @@ var rand = uniform( -10.0, 10.0 );
* @returns {Function} benchmark function
*/
function createBenchmark( len ) {
var x = filledarrayBy( len, 'float64', rand );
var x = uniform( len, -10.0, 10.0, options );
return benchmark;

function benchmark( b ) {
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -94,7 +94,7 @@ static double rand_double( void ) {
* @param len array length
* @return elapsed time in seconds
*/
static double benchmark( int iterations, int len ) {
static double benchmark1( int iterations, int len ) {
double elapsed;
double x[ len ];
double t;
Expand All @@ -105,7 +105,38 @@ static double benchmark( int iterations, int len ) {
}
t = tic();
for ( i = 0; i < iterations; i++ ) {
c_drev( len, x, 1 );
stdlib_strided_drev( len, x, 1 );
if ( x[ 0 ] != x[ 0 ] ) {
printf( "should not return NaN\n" );
break;
}
}
elapsed = tic() - t;
if ( x[ 0 ] != x[ 0 ] ) {
printf( "should not return NaN\n" );
}
return elapsed;
}

/**
* Runs a benchmark.
*
* @param iterations number of iterations
* @param len array length
* @return elapsed time in seconds
*/
static double benchmark2( int iterations, int len ) {
double elapsed;
double x[ len ];
double t;
int i;

for ( i = 0; i < len; i++ ) {
x[ i ] = ( rand_double()*200.0 ) - 100.0;
}
t = tic();
for ( i = 0; i < iterations; i++ ) {
stdlib_strided_drev_ndarray( len, x, 1, 0 );
if ( x[ 0 ] != x[ 0 ] ) {
printf( "should not return NaN\n" );
break;
Expand Down Expand Up @@ -140,7 +171,18 @@ int main( void ) {
for ( j = 0; j < REPEATS; j++ ) {
count += 1;
printf( "# c::%s:len=%d\n", NAME, len );
elapsed = benchmark( iter, len );
elapsed = benchmark1( iter, len );
print_results( iter, elapsed );
printf( "ok %d benchmark finished\n", count );
}
}
for ( i = MIN; i <= MAX; i++ ) {
len = pow( 10, i );
iter = ITERATIONS / pow( 10, i-1 );
for ( j = 0; j < REPEATS; j++ ) {
count += 1;
printf( "# c::%s:ndarray:len=%d\n", NAME, len );
elapsed = benchmark2( iter, len );
print_results( iter, elapsed );
printf( "ok %d benchmark finished\n", count );
}
Expand Down
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