|
| 1 | +<!-- |
| 2 | +
|
| 3 | +@license Apache-2.0 |
| 4 | +
|
| 5 | +Copyright (c) 2026 The Stdlib Authors. |
| 6 | +
|
| 7 | +Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | +you may not use this file except in compliance with the License. |
| 9 | +You may obtain a copy of the License at |
| 10 | +
|
| 11 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | +
|
| 13 | +Unless required by applicable law or agreed to in writing, software |
| 14 | +distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | +See the License for the specific language governing permissions and |
| 17 | +limitations under the License. |
| 18 | +
|
| 19 | +--> |
| 20 | + |
| 21 | +# scartesianPower |
| 22 | + |
| 23 | +> Compute the Cartesian power for a single-precision floating-point strided array. |
| 24 | +
|
| 25 | +<section class="usage"> |
| 26 | + |
| 27 | +## Usage |
| 28 | + |
| 29 | +```javascript |
| 30 | +var scartesianPower = require( '@stdlib/blas/ext/base/scartesian-power' ); |
| 31 | +``` |
| 32 | + |
| 33 | +#### scartesianPower( order, N, k, x, strideX, out, LDO ) |
| 34 | + |
| 35 | +Computes the Cartesian power for a single-precision floating-point strided array. |
| 36 | + |
| 37 | +```javascript |
| 38 | +var Float32Array = require( '@stdlib/array/float32' ); |
| 39 | + |
| 40 | +var x = new Float32Array( [ 1.0, 2.0 ] ); |
| 41 | +var out = new Float32Array( 8 ); |
| 42 | + |
| 43 | +scartesianPower( 'row-major', x.length, 2, x, 1, out, 2 ); |
| 44 | +// out => <Float32Array>[ 1.0, 1.0, 1.0, 2.0, 2.0, 1.0, 2.0, 2.0 ] |
| 45 | +``` |
| 46 | + |
| 47 | +The function has the following parameters: |
| 48 | + |
| 49 | +- **order**: storage layout. Must be either `'row-major'` or `'column-major'`. |
| 50 | +- **N**: number of indexed elements. |
| 51 | +- **k**: power. |
| 52 | +- **x**: input [`Float32Array`][@stdlib/array/float32]. |
| 53 | +- **strideX**: stride length for `x`. |
| 54 | +- **out**: output [`Float32Array`][@stdlib/array/float32]. |
| 55 | +- **LDO**: stride length between successive contiguous vectors of the matrix `out` (a.k.a., leading dimension of `out`). |
| 56 | + |
| 57 | +The `N`, `k`, and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to compute the Cartesian power of every other element: |
| 58 | + |
| 59 | +```javascript |
| 60 | +var Float32Array = require( '@stdlib/array/float32' ); |
| 61 | + |
| 62 | +var x = new Float32Array( [ 1.0, 0.0, 2.0, 0.0 ] ); |
| 63 | +var out = new Float32Array( 8 ); |
| 64 | + |
| 65 | +scartesianPower( 'row-major', 2, 2, x, 2, out, 2 ); |
| 66 | +// out => <Float32Array>[ 1.0, 1.0, 1.0, 2.0, 2.0, 1.0, 2.0, 2.0 ] |
| 67 | +``` |
| 68 | + |
| 69 | +Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views. |
| 70 | + |
| 71 | +```javascript |
| 72 | +var Float32Array = require( '@stdlib/array/float32' ); |
| 73 | + |
| 74 | +// Initial array: |
| 75 | +var x0 = new Float32Array( [ 0.0, 1.0, 2.0, 3.0 ] ); |
| 76 | + |
| 77 | +// Create an offset view: |
| 78 | +var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element |
| 79 | + |
| 80 | +// Output array: |
| 81 | +var out = new Float32Array( 8 ); |
| 82 | + |
| 83 | +scartesianPower( 'row-major', 2, 2, x1, 1, out, 2 ); |
| 84 | +// out => <Float32Array>[ 1.0, 1.0, 1.0, 2.0, 2.0, 1.0, 2.0, 2.0 ] |
| 85 | +``` |
| 86 | + |
| 87 | +<!-- lint disable maximum-heading-length --> |
| 88 | + |
| 89 | +#### scartesianPower.ndarray( N, k, x, strideX, offsetX, out, strideOut1, strideOut2, offsetOut ) |
| 90 | + |
| 91 | +<!-- lint enable maximum-heading-length --> |
| 92 | + |
| 93 | +Computes the Cartesian power for a single-precision floating-point strided array using alternative indexing semantics. |
| 94 | + |
| 95 | +```javascript |
| 96 | +var Float32Array = require( '@stdlib/array/float32' ); |
| 97 | + |
| 98 | +var x = new Float32Array( [ 1.0, 2.0 ] ); |
| 99 | +var out = new Float32Array( 8 ); |
| 100 | + |
| 101 | +scartesianPower.ndarray( x.length, 2, x, 1, 0, out, 2, 1, 0 ); |
| 102 | +// out => <Float32Array>[ 1.0, 1.0, 1.0, 2.0, 2.0, 1.0, 2.0, 2.0 ] |
| 103 | +``` |
| 104 | + |
| 105 | +The function has the following parameters: |
| 106 | + |
| 107 | +- **N**: number of indexed elements. |
| 108 | +- **k**: power. |
| 109 | +- **x**: input [`Float32Array`][@stdlib/array/float32]. |
| 110 | +- **strideX**: stride length for `x`. |
| 111 | +- **offsetX**: starting index for `x`. |
| 112 | +- **out**: output [`Float32Array`][@stdlib/array/float32]. |
| 113 | +- **strideOut1**: stride length of the first dimension of `out`. |
| 114 | +- **strideOut2**: stride length of the second dimension of `out`. |
| 115 | +- **offsetOut**: starting index for `out`. |
| 116 | + |
| 117 | +While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameters support indexing semantics based on starting indices. For example, to access only the last two elements: |
| 118 | + |
| 119 | +```javascript |
| 120 | +var Float32Array = require( '@stdlib/array/float32' ); |
| 121 | + |
| 122 | +var x = new Float32Array( [ 0.0, 0.0, 1.0, 2.0 ] ); |
| 123 | +var out = new Float32Array( 8 ); |
| 124 | + |
| 125 | +scartesianPower.ndarray( 2, 2, x, 1, 2, out, 2, 1, 0 ); |
| 126 | +// out => <Float32Array>[ 1.0, 1.0, 1.0, 2.0, 2.0, 1.0, 2.0, 2.0 ] |
| 127 | +``` |
| 128 | + |
| 129 | +</section> |
| 130 | + |
| 131 | +<!-- /.usage --> |
| 132 | + |
| 133 | +<section class="notes"> |
| 134 | + |
| 135 | +## Notes |
| 136 | + |
| 137 | +- `k`-tuples are stored as rows in the output matrix, where the `j`-th column contains the `j`-th element of each tuple. |
| 138 | +- For an input array of length `N`, the output array must contain at least `N^k * k` indexed elements. |
| 139 | +- For row-major order, the `LDO` parameter must be greater than or equal to `max(1,k)`. For column-major order, the `LDO` parameter must be greater than or equal to `max(1,N^k)`. |
| 140 | +- If `N <= 0` or `k <= 0`, both functions return `out` unchanged. |
| 141 | + |
| 142 | +</section> |
| 143 | + |
| 144 | +<!-- /.notes --> |
| 145 | + |
| 146 | +<section class="examples"> |
| 147 | + |
| 148 | +## Examples |
| 149 | + |
| 150 | +<!-- eslint no-undef: "error" --> |
| 151 | + |
| 152 | +```javascript |
| 153 | +var discreteUniform = require( '@stdlib/random/array/discrete-uniform' ); |
| 154 | +var Float32Array = require( '@stdlib/array/float32' ); |
| 155 | +var pow = require( '@stdlib/math/base/special/pow' ); |
| 156 | +var scartesianPower = require( '@stdlib/blas/ext/base/scartesian-power' ); |
| 157 | + |
| 158 | +var N = 2; |
| 159 | +var k = 3; |
| 160 | +var x = discreteUniform( N, 1, 10, { |
| 161 | + 'dtype': 'float32' |
| 162 | +}); |
| 163 | +console.log( x ); |
| 164 | + |
| 165 | +var out = new Float32Array( pow( N, k ) * k ); |
| 166 | +scartesianPower( 'row-major', N, k, x, 1, out, k ); |
| 167 | +console.log( out ); |
| 168 | +``` |
| 169 | + |
| 170 | +</section> |
| 171 | + |
| 172 | +<!-- /.examples --> |
| 173 | + |
| 174 | +<!-- C interface documentation. --> |
| 175 | + |
| 176 | +* * * |
| 177 | + |
| 178 | +<section class="c"> |
| 179 | + |
| 180 | +## C APIs |
| 181 | + |
| 182 | +<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. --> |
| 183 | + |
| 184 | +<section class="intro"> |
| 185 | + |
| 186 | +</section> |
| 187 | + |
| 188 | +<!-- /.intro --> |
| 189 | + |
| 190 | +<!-- C usage documentation. --> |
| 191 | + |
| 192 | +<section class="usage"> |
| 193 | + |
| 194 | +### Usage |
| 195 | + |
| 196 | +```c |
| 197 | +#include "stdlib/blas/ext/base/scartesianpower.h" |
| 198 | +``` |
| 199 | + |
| 200 | +#### stdlib_strided_scartesian_power( order, N, k, \*X, strideX, \*Out, LDO ) |
| 201 | + |
| 202 | +Computes the Cartesian power for a single-precision floating-point strided array. |
| 203 | + |
| 204 | +```c |
| 205 | +#include "stdlib/blas/base/shared.h" |
| 206 | + |
| 207 | +const float x[] = { 1.0f, 2.0f }; |
| 208 | +float out[ 8 ]; |
| 209 | + |
| 210 | +stdlib_strided_scartesian_power( CblasRowMajor, 2, 2, x, 1, out, 2 ); |
| 211 | +``` |
| 212 | +
|
| 213 | +The function accepts the following arguments: |
| 214 | +
|
| 215 | +- **order**: `[in] CBLAS_LAYOUT` storage layout. |
| 216 | +- **N**: `[in] CBLAS_INT` number of indexed elements. |
| 217 | +- **k**: `[in] CBLAS_INT` power. |
| 218 | +- **X**: `[in] float*` input array. |
| 219 | +- **strideX**: `[in] CBLAS_INT` stride length for `X`. |
| 220 | +- **Out**: `[out] float*` output array. |
| 221 | +- **LDO**: `[in] CBLAS_INT` stride length between successive contiguous vectors of the matrix `Out` (a.k.a., leading dimension of `Out`). For row-major order, must be greater than or equal to `max(1,k)`. For column-major order, must be greater than or equal to `max(1,N^k)`. |
| 222 | +
|
| 223 | +```c |
| 224 | +void stdlib_strided_scartesian_power( const CBLAS_LAYOUT order, const CBLAS_INT N, const CBLAS_INT k, const float *X, const CBLAS_INT strideX, float *Out, const CBLAS_INT LDO ); |
| 225 | +``` |
| 226 | + |
| 227 | +<!-- lint disable maximum-heading-length --> |
| 228 | + |
| 229 | +#### stdlib_strided_scartesian_power_ndarray( N, k, \*X, strideX, offsetX, \*Out, strideOut1, strideOut2, offsetOut ) |
| 230 | + |
| 231 | +<!-- lint enable maximum-heading-length --> |
| 232 | + |
| 233 | +Computes the Cartesian power for a single-precision floating-point strided array using alternative indexing semantics. |
| 234 | + |
| 235 | +```c |
| 236 | +const float x[] = { 1.0f, 2.0f }; |
| 237 | +float out[ 8 ]; |
| 238 | + |
| 239 | +stdlib_strided_scartesian_power_ndarray( 2, 2, x, 1, 0, out, 2, 1, 0 ); |
| 240 | +``` |
| 241 | +
|
| 242 | +The function accepts the following arguments: |
| 243 | +
|
| 244 | +- **N**: `[in] CBLAS_INT` number of indexed elements. |
| 245 | +- **k**: `[in] CBLAS_INT` power. |
| 246 | +- **X**: `[in] float*` input array. |
| 247 | +- **strideX**: `[in] CBLAS_INT` stride length for `X`. |
| 248 | +- **offsetX**: `[in] CBLAS_INT` starting index for `X`. |
| 249 | +- **Out**: `[out] float*` output array. |
| 250 | +- **strideOut1**: `[in] CBLAS_INT` stride length of the first dimension of `Out`. |
| 251 | +- **strideOut2**: `[in] CBLAS_INT` stride length of the second dimension of `Out`. |
| 252 | +- **offsetOut**: `[in] CBLAS_INT` starting index for `Out`. |
| 253 | +
|
| 254 | +```c |
| 255 | +void stdlib_strided_scartesian_power_ndarray( const CBLAS_INT N, const CBLAS_INT k, const float *X, const CBLAS_INT strideX, const CBLAS_INT offsetX, float *Out, const CBLAS_INT strideOut1, const CBLAS_INT strideOut2, const CBLAS_INT offsetOut ); |
| 256 | +``` |
| 257 | + |
| 258 | +</section> |
| 259 | + |
| 260 | +<!-- /.usage --> |
| 261 | + |
| 262 | +<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 263 | + |
| 264 | +<section class="notes"> |
| 265 | + |
| 266 | +</section> |
| 267 | + |
| 268 | +<!-- /.notes --> |
| 269 | + |
| 270 | +<!-- C API usage examples. --> |
| 271 | + |
| 272 | +<section class="examples"> |
| 273 | + |
| 274 | +### Examples |
| 275 | + |
| 276 | +```c |
| 277 | +#include "stdlib/blas/ext/base/scartesianpower.h" |
| 278 | +#include "stdlib/blas/base/shared.h" |
| 279 | +#include <stdio.h> |
| 280 | +#include <math.h> |
| 281 | + |
| 282 | +int main( void ) { |
| 283 | + // Create a strided input array: |
| 284 | + const float x[] = { 1.0f, 2.0f }; |
| 285 | + |
| 286 | + // Specify the number of indexed elements and power: |
| 287 | + const int N = 2; |
| 288 | + const int k = 2; |
| 289 | + |
| 290 | + // Create an output array (N^k tuples, each tuple has k elements): |
| 291 | + float out[ 8 ]; |
| 292 | + |
| 293 | + // Specify strides: |
| 294 | + const int strideX = 1; |
| 295 | + const int LDO = 2; |
| 296 | + |
| 297 | + // Compute the Cartesian power: |
| 298 | + stdlib_strided_scartesian_power( CblasRowMajor, N, k, x, strideX, out, LDO ); |
| 299 | + |
| 300 | + // Print the result: |
| 301 | + const int len = (int)pow( N, k ); |
| 302 | + for ( int i = 0; i < len; i++ ) { |
| 303 | + printf( "out[ %i ] = ( %f, %f )\n", i, out[ i*2 ], out[ (i*2)+1 ] ); |
| 304 | + } |
| 305 | +} |
| 306 | +``` |
| 307 | +
|
| 308 | +</section> |
| 309 | +
|
| 310 | +<!-- /.examples --> |
| 311 | +
|
| 312 | +</section> |
| 313 | +
|
| 314 | +<!-- /.c --> |
| 315 | +
|
| 316 | +<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. --> |
| 317 | +
|
| 318 | +<section class="related"> |
| 319 | +
|
| 320 | +</section> |
| 321 | +
|
| 322 | +<!-- /.related --> |
| 323 | +
|
| 324 | +<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 325 | +
|
| 326 | +<section class="links"> |
| 327 | +
|
| 328 | +[@stdlib/array/float32]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/float32 |
| 329 | +
|
| 330 | +[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray |
| 331 | +
|
| 332 | +</section> |
| 333 | +
|
| 334 | +<!-- /.links --> |
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