|
| 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 | +# dcartesianSquare |
| 22 | + |
| 23 | +> Compute the Cartesian square for a double-precision floating-point strided array. |
| 24 | +
|
| 25 | +<section class="usage"> |
| 26 | + |
| 27 | +## Usage |
| 28 | + |
| 29 | +```javascript |
| 30 | +var dcartesianSquare = require( '@stdlib/blas/ext/base/dcartesian-square' ); |
| 31 | +``` |
| 32 | + |
| 33 | +#### dcartesianSquare( order, N, x, strideX, out, LDO ) |
| 34 | + |
| 35 | +Computes the Cartesian square for a double-precision floating-point strided array. |
| 36 | + |
| 37 | +```javascript |
| 38 | +var Float64Array = require( '@stdlib/array/float64' ); |
| 39 | + |
| 40 | +var x = new Float64Array( [ 1.0, 2.0 ] ); |
| 41 | +var out = new Float64Array( 8 ); |
| 42 | + |
| 43 | +dcartesianSquare( 'row-major', x.length, x, 1, out, 2 ); |
| 44 | +// out => <Float64Array>[ 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 | +- **x**: input [`Float64Array`][@stdlib/array/float64]. |
| 52 | +- **strideX**: stride length for `x`. |
| 53 | +- **out**: output [`Float64Array`][@stdlib/array/float64]. |
| 54 | +- **LDO**: stride length between successive contiguous vectors of the matrix `out` (a.k.a., leading dimension of `out`). |
| 55 | + |
| 56 | +The `N` and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to compute the Cartesian square of every other element: |
| 57 | + |
| 58 | +```javascript |
| 59 | +var Float64Array = require( '@stdlib/array/float64' ); |
| 60 | + |
| 61 | +var x = new Float64Array( [ 1.0, 0.0, 2.0, 0.0 ] ); |
| 62 | +var out = new Float64Array( 8 ); |
| 63 | + |
| 64 | +dcartesianSquare( 'row-major', 2, x, 2, out, 2 ); |
| 65 | +// out => <Float64Array>[ 1.0, 1.0, 1.0, 2.0, 2.0, 1.0, 2.0, 2.0 ] |
| 66 | +``` |
| 67 | + |
| 68 | +Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views. |
| 69 | + |
| 70 | +```javascript |
| 71 | +var Float64Array = require( '@stdlib/array/float64' ); |
| 72 | + |
| 73 | +// Initial array: |
| 74 | +var x0 = new Float64Array( [ 0.0, 1.0, 2.0, 3.0 ] ); |
| 75 | + |
| 76 | +// Create an offset view: |
| 77 | +var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element |
| 78 | + |
| 79 | +// Output array: |
| 80 | +var out = new Float64Array( 8 ); |
| 81 | + |
| 82 | +dcartesianSquare( 'row-major', 2, x1, 1, out, 2 ); |
| 83 | +// out => <Float64Array>[ 1.0, 1.0, 1.0, 2.0, 2.0, 1.0, 2.0, 2.0 ] |
| 84 | +``` |
| 85 | + |
| 86 | +<!-- lint disable maximum-heading-length --> |
| 87 | + |
| 88 | +#### dcartesianSquare.ndarray( N, x, strideX, offsetX, out, strideOut1, strideOut2, offsetOut ) |
| 89 | + |
| 90 | +<!-- lint enable maximum-heading-length --> |
| 91 | + |
| 92 | +Computes the Cartesian square for a double-precision floating-point strided array using alternative indexing semantics. |
| 93 | + |
| 94 | +```javascript |
| 95 | +var Float64Array = require( '@stdlib/array/float64' ); |
| 96 | + |
| 97 | +var x = new Float64Array( [ 1.0, 2.0 ] ); |
| 98 | +var out = new Float64Array( 8 ); |
| 99 | + |
| 100 | +dcartesianSquare.ndarray( x.length, x, 1, 0, out, 2, 1, 0 ); |
| 101 | +// out => <Float64Array>[ 1.0, 1.0, 1.0, 2.0, 2.0, 1.0, 2.0, 2.0 ] |
| 102 | +``` |
| 103 | + |
| 104 | +The function has the following parameters: |
| 105 | + |
| 106 | +- **N**: number of indexed elements. |
| 107 | +- **x**: input [`Float64Array`][@stdlib/array/float64]. |
| 108 | +- **strideX**: stride length for `x`. |
| 109 | +- **offsetX**: starting index for `x`. |
| 110 | +- **out**: output [`Float64Array`][@stdlib/array/float64]. |
| 111 | +- **strideOut1**: stride length of the first dimension of `out`. |
| 112 | +- **strideOut2**: stride length of the second dimension of `out`. |
| 113 | +- **offsetOut**: starting index for `out`. |
| 114 | + |
| 115 | +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: |
| 116 | + |
| 117 | +```javascript |
| 118 | +var Float64Array = require( '@stdlib/array/float64' ); |
| 119 | + |
| 120 | +var x = new Float64Array( [ 0.0, 0.0, 1.0, 2.0 ] ); |
| 121 | +var out = new Float64Array( 8 ); |
| 122 | + |
| 123 | +dcartesianSquare.ndarray( 2, x, 1, 2, out, 2, 1, 0 ); |
| 124 | +// out => <Float64Array>[ 1.0, 1.0, 1.0, 2.0, 2.0, 1.0, 2.0, 2.0 ] |
| 125 | +``` |
| 126 | + |
| 127 | +</section> |
| 128 | + |
| 129 | +<!-- /.usage --> |
| 130 | + |
| 131 | +<section class="notes"> |
| 132 | + |
| 133 | +## Notes |
| 134 | + |
| 135 | +- Pairs are stored as rows in the output matrix, where the first column contains the first element of each pair and the second column contains the second element. |
| 136 | +- For an input array of length `N`, the output array must contain at least `N * N * 2` indexed elements. |
| 137 | +- For row-major order, the `LDO` parameter must be greater than or equal to `2`. For column-major order, the `LDO` parameter must be greater than or equal to `max(1,N*N)`. |
| 138 | +- If `N <= 0`, both functions return `out` unchanged. |
| 139 | + |
| 140 | +</section> |
| 141 | + |
| 142 | +<!-- /.notes --> |
| 143 | + |
| 144 | +<section class="examples"> |
| 145 | + |
| 146 | +## Examples |
| 147 | + |
| 148 | +<!-- eslint no-undef: "error" --> |
| 149 | + |
| 150 | +```javascript |
| 151 | +var discreteUniform = require( '@stdlib/random/array/discrete-uniform' ); |
| 152 | +var Float64Array = require( '@stdlib/array/float64' ); |
| 153 | +var dcartesianSquare = require( '@stdlib/blas/ext/base/dcartesian-square' ); |
| 154 | + |
| 155 | +var N = 2; |
| 156 | +var x = discreteUniform( N, 1, 10, { |
| 157 | + 'dtype': 'float64' |
| 158 | +}); |
| 159 | +console.log( x ); |
| 160 | + |
| 161 | +var out = new Float64Array( N * N * 2 ); |
| 162 | +dcartesianSquare( 'row-major', N, x, 1, out, 2 ); |
| 163 | +console.log( out ); |
| 164 | +``` |
| 165 | + |
| 166 | +</section> |
| 167 | + |
| 168 | +<!-- /.examples --> |
| 169 | + |
| 170 | +<!-- C interface documentation. --> |
| 171 | + |
| 172 | +* * * |
| 173 | + |
| 174 | +<section class="c"> |
| 175 | + |
| 176 | +## C APIs |
| 177 | + |
| 178 | +<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. --> |
| 179 | + |
| 180 | +<section class="intro"> |
| 181 | + |
| 182 | +</section> |
| 183 | + |
| 184 | +<!-- /.intro --> |
| 185 | + |
| 186 | +<!-- C usage documentation. --> |
| 187 | + |
| 188 | +<section class="usage"> |
| 189 | + |
| 190 | +### Usage |
| 191 | + |
| 192 | +```c |
| 193 | +#include "stdlib/blas/ext/base/dcartesiansquare.h" |
| 194 | +``` |
| 195 | + |
| 196 | +#### stdlib_strided_dcartesian_square( order, N, \*X, strideX, \*Out, LDO ) |
| 197 | + |
| 198 | +Computes the Cartesian square for a double-precision floating-point strided array. |
| 199 | + |
| 200 | +```c |
| 201 | +#include "stdlib/blas/base/shared.h" |
| 202 | + |
| 203 | +const double x[] = { 1.0, 2.0 }; |
| 204 | +double out[ 8 ]; |
| 205 | + |
| 206 | +stdlib_strided_dcartesian_square( CblasRowMajor, 2, x, 1, out, 2 ); |
| 207 | +``` |
| 208 | +
|
| 209 | +The function accepts the following arguments: |
| 210 | +
|
| 211 | +- **order**: `[in] CBLAS_LAYOUT` storage layout. |
| 212 | +- **N**: `[in] CBLAS_INT` number of indexed elements. |
| 213 | +- **X**: `[in] double*` input array. |
| 214 | +- **strideX**: `[in] CBLAS_INT` stride length for `X`. |
| 215 | +- **Out**: `[out] double*` output array. |
| 216 | +- **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 `2`. For column-major order, must be greater than or equal to `max(1,N*N)`. |
| 217 | +
|
| 218 | +```c |
| 219 | +void stdlib_strided_dcartesian_square( const CBLAS_LAYOUT order, const CBLAS_INT N, const double *X, const CBLAS_INT strideX, double *Out, const CBLAS_INT LDO ); |
| 220 | +``` |
| 221 | + |
| 222 | +<!-- lint disable maximum-heading-length --> |
| 223 | + |
| 224 | +#### stdlib_strided_dcartesian_square_ndarray( N, \*X, strideX, offsetX, \*Out, strideOut1, strideOut2, offsetOut ) |
| 225 | + |
| 226 | +<!-- lint enable maximum-heading-length --> |
| 227 | + |
| 228 | +Computes the Cartesian square for a double-precision floating-point strided array using alternative indexing semantics. |
| 229 | + |
| 230 | +```c |
| 231 | +const double x[] = { 1.0, 2.0 }; |
| 232 | +double out[ 8 ]; |
| 233 | + |
| 234 | +stdlib_strided_dcartesian_square_ndarray( 2, x, 1, 0, out, 2, 1, 0 ); |
| 235 | +``` |
| 236 | +
|
| 237 | +The function accepts the following arguments: |
| 238 | +
|
| 239 | +- **N**: `[in] CBLAS_INT` number of indexed elements. |
| 240 | +- **X**: `[in] double*` input array. |
| 241 | +- **strideX**: `[in] CBLAS_INT` stride length for `X`. |
| 242 | +- **offsetX**: `[in] CBLAS_INT` starting index for `X`. |
| 243 | +- **Out**: `[out] double*` output array. |
| 244 | +- **strideOut1**: `[in] CBLAS_INT` stride length of the first dimension of `Out`. |
| 245 | +- **strideOut2**: `[in] CBLAS_INT` stride length of the second dimension of `Out`. |
| 246 | +- **offsetOut**: `[in] CBLAS_INT` starting index for `Out`. |
| 247 | +
|
| 248 | +```c |
| 249 | +void stdlib_strided_dcartesian_square_ndarray( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX, double *Out, const CBLAS_INT strideOut1, const CBLAS_INT strideOut2, const CBLAS_INT offsetOut ); |
| 250 | +``` |
| 251 | + |
| 252 | +</section> |
| 253 | + |
| 254 | +<!-- /.usage --> |
| 255 | + |
| 256 | +<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 257 | + |
| 258 | +<section class="notes"> |
| 259 | + |
| 260 | +</section> |
| 261 | + |
| 262 | +<!-- /.notes --> |
| 263 | + |
| 264 | +<!-- C API usage examples. --> |
| 265 | + |
| 266 | +<section class="examples"> |
| 267 | + |
| 268 | +### Examples |
| 269 | + |
| 270 | +```c |
| 271 | +#include "stdlib/blas/ext/base/dcartesiansquare.h" |
| 272 | +#include "stdlib/blas/base/shared.h" |
| 273 | +#include <stdio.h> |
| 274 | + |
| 275 | +int main( void ) { |
| 276 | + // Create a strided input array: |
| 277 | + const double x[] = { 1.0, 2.0 }; |
| 278 | + |
| 279 | + // Specify the number of indexed elements: |
| 280 | + const int N = 2; |
| 281 | + |
| 282 | + // Create an output array (N*N pairs, each pair has 2 elements): |
| 283 | + double out[ 8 ]; |
| 284 | + |
| 285 | + // Specify strides: |
| 286 | + const int strideX = 1; |
| 287 | + const int LDO = 2; |
| 288 | + |
| 289 | + // Compute the Cartesian square: |
| 290 | + stdlib_strided_dcartesian_square( CblasRowMajor, N, x, strideX, out, LDO ); |
| 291 | + |
| 292 | + // Print the result: |
| 293 | + for ( int i = 0; i < N*N; i++ ) { |
| 294 | + printf( "out[ %i ] = ( %lf, %lf )\n", i, out[ i*2 ], out[ (i*2)+1 ] ); |
| 295 | + } |
| 296 | +} |
| 297 | +``` |
| 298 | +
|
| 299 | +</section> |
| 300 | +
|
| 301 | +<!-- /.examples --> |
| 302 | +
|
| 303 | +</section> |
| 304 | +
|
| 305 | +<!-- /.c --> |
| 306 | +
|
| 307 | +<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. --> |
| 308 | +
|
| 309 | +<section class="related"> |
| 310 | +
|
| 311 | +</section> |
| 312 | +
|
| 313 | +<!-- /.related --> |
| 314 | +
|
| 315 | +<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 316 | +
|
| 317 | +<section class="links"> |
| 318 | +
|
| 319 | +[@stdlib/array/float64]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/float64 |
| 320 | +
|
| 321 | +[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray |
| 322 | +
|
| 323 | +</section> |
| 324 | +
|
| 325 | +<!-- /.links --> |
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