|
| 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 | +# cxsa |
| 22 | + |
| 23 | +> Subtract a scalar constant from each element in a single-precision complex floating-point strided array. |
| 24 | +
|
| 25 | +<section class="usage"> |
| 26 | + |
| 27 | +## Usage |
| 28 | + |
| 29 | +```javascript |
| 30 | +var cxsa = require( '@stdlib/blas/ext/base/cxsa' ); |
| 31 | +``` |
| 32 | + |
| 33 | +#### cxsa( N, alpha, x, strideX ) |
| 34 | + |
| 35 | +Subtracts a scalar constant from each element in a single-precision complex floating-point strided array. |
| 36 | + |
| 37 | +```javascript |
| 38 | +var Complex64Array = require( '@stdlib/array/complex64' ); |
| 39 | +var Complex64 = require( '@stdlib/complex/float32/ctor' ); |
| 40 | + |
| 41 | +var x = new Complex64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] ); |
| 42 | + |
| 43 | +var alpha = new Complex64( 5.0, 0.0 ); |
| 44 | + |
| 45 | +cxsa( x.length, alpha, x, 1 ); |
| 46 | +// x => <Complex64Array>[ -7.0, 1.0, -2.0, -5.0, -1.0, 0.0, -6.0, -3.0 ] |
| 47 | +``` |
| 48 | + |
| 49 | +The function has the following parameters: |
| 50 | + |
| 51 | +- **N**: number of indexed elements. |
| 52 | +- **alpha**: scalar constant. |
| 53 | +- **x**: input [`Complex64Array`][@stdlib/array/complex64]. |
| 54 | +- **strideX**: stride length. |
| 55 | + |
| 56 | +The `N` and stride parameters determine which elements in the strided array are accessed at runtime. For example, to add a constant to every other element: |
| 57 | + |
| 58 | +```javascript |
| 59 | +var Complex64Array = require( '@stdlib/array/complex64' ); |
| 60 | +var Complex64 = require( '@stdlib/complex/float32/ctor' ); |
| 61 | + |
| 62 | +var x = new Complex64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] ); |
| 63 | + |
| 64 | +var alpha = new Complex64( 5.0, 0.0 ); |
| 65 | + |
| 66 | +cxsa( 2, alpha, x, 2 ); |
| 67 | +// x => <Complex64Array>[ -7.0, 1.0, 3.0, -5.0, -1.0, 0.0, -1.0, -3.0 ] |
| 68 | +``` |
| 69 | + |
| 70 | +Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views. |
| 71 | + |
| 72 | +```javascript |
| 73 | +var Complex64Array = require( '@stdlib/array/complex64' ); |
| 74 | +var Complex64 = require( '@stdlib/complex/float32/ctor' ); |
| 75 | + |
| 76 | +// Initial array: |
| 77 | +var x0 = new Complex64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] ); |
| 78 | + |
| 79 | +// Create an offset view: |
| 80 | +var x1 = new Complex64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element |
| 81 | + |
| 82 | +// Define a scalar constant: |
| 83 | +var alpha = new Complex64( 5.0, 0.0 ); |
| 84 | + |
| 85 | +// Subtract a constant from each element starting from the second element: |
| 86 | +cxsa( 2, alpha, x1, 1 ); |
| 87 | +// x0 => <Complex64Array>[ 1.0, -2.0, -2.0, -4.0, 0.0, -6.0 ] |
| 88 | +``` |
| 89 | + |
| 90 | +#### cxsa.ndarray( N, alpha, x, strideX, offsetX ) |
| 91 | + |
| 92 | +Subtracts a scalar constant from each element in a single-precision complex floating-point strided array using alternative indexing semantics. |
| 93 | + |
| 94 | +```javascript |
| 95 | +var Complex64Array = require( '@stdlib/array/complex64' ); |
| 96 | +var Complex64 = require( '@stdlib/complex/float32/ctor' ); |
| 97 | + |
| 98 | +var x = new Complex64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] ); |
| 99 | + |
| 100 | +var alpha = new Complex64( 5.0, 0.0 ); |
| 101 | + |
| 102 | +cxsa.ndarray( x.length, alpha, x, 1, 0 ); |
| 103 | +// x => <Complex64Array>[ -7.0, 1.0, -2.0, -5.0, -1.0, 0.0, -6.0, -3.0 ] |
| 104 | +``` |
| 105 | + |
| 106 | +The function has the following additional parameters: |
| 107 | + |
| 108 | +- **offsetX**: starting index. |
| 109 | + |
| 110 | +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 two elements of the strided array: |
| 111 | + |
| 112 | +```javascript |
| 113 | +var Complex64Array = require( '@stdlib/array/complex64' ); |
| 114 | +var Complex64 = require( '@stdlib/complex/float32/ctor' ); |
| 115 | + |
| 116 | +var x = new Complex64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0, 7.0, -8.0 ] ); |
| 117 | + |
| 118 | +var alpha = new Complex64( 5.0, 0.0 ); |
| 119 | + |
| 120 | +cxsa.ndarray( 2, alpha, x, 1, 2 ); |
| 121 | +// x => <Complex64Array>[ 1.0, -2.0, 3.0, -4.0, 0.0, -6.0, 2.0, -8.0 ] |
| 122 | +``` |
| 123 | + |
| 124 | +</section> |
| 125 | + |
| 126 | +<!-- /.usage --> |
| 127 | + |
| 128 | +<section class="notes"> |
| 129 | + |
| 130 | +## Notes |
| 131 | + |
| 132 | +- If `N <= 0`, both functions return the strided array unchanged. |
| 133 | + |
| 134 | +</section> |
| 135 | + |
| 136 | +<!-- /.notes --> |
| 137 | + |
| 138 | +<section class="examples"> |
| 139 | + |
| 140 | +## Examples |
| 141 | + |
| 142 | +<!-- eslint no-undef: "error" --> |
| 143 | + |
| 144 | +```javascript |
| 145 | +var discreteUniform = require( '@stdlib/random/array/discrete-uniform' ); |
| 146 | +var Complex64Array = require( '@stdlib/array/complex64' ); |
| 147 | +var Complex64 = require( '@stdlib/complex/float32/ctor' ); |
| 148 | +var logEach = require( '@stdlib/console/log-each' ); |
| 149 | +var cxsa = require( '@stdlib/blas/ext/base/cxsa' ); |
| 150 | + |
| 151 | +var xbuf = discreteUniform( 20, -100, 100, { |
| 152 | + 'dtype': 'float32' |
| 153 | +}); |
| 154 | +var x = new Complex64Array( xbuf.buffer ); |
| 155 | +var alpha = new Complex64( 10.0, 10.0 ); |
| 156 | + |
| 157 | +cxsa( x.length, alpha, x, 1 ); |
| 158 | +logEach( '%s', x ); |
| 159 | +``` |
| 160 | + |
| 161 | +</section> |
| 162 | + |
| 163 | +<!-- /.examples --> |
| 164 | + |
| 165 | +<!-- C interface documentation. --> |
| 166 | + |
| 167 | +* * * |
| 168 | + |
| 169 | +<section class="c"> |
| 170 | + |
| 171 | +## C APIs |
| 172 | + |
| 173 | +<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. --> |
| 174 | + |
| 175 | +<section class="intro"> |
| 176 | + |
| 177 | +</section> |
| 178 | + |
| 179 | +<!-- /.intro --> |
| 180 | + |
| 181 | +<!-- C usage documentation. --> |
| 182 | + |
| 183 | +<section class="usage"> |
| 184 | + |
| 185 | +### Usage |
| 186 | + |
| 187 | +```c |
| 188 | +#include "stdlib/blas/ext/base/cxsa.h" |
| 189 | +``` |
| 190 | + |
| 191 | +#### stdlib_strided_cxsa( N, alpha, \*X, strideX ) |
| 192 | + |
| 193 | +Subtracts a scalar constant from each element in a single-precision complex floating-point strided array. |
| 194 | + |
| 195 | +```c |
| 196 | +#include "stdlib/complex/float32/ctor.h" |
| 197 | + |
| 198 | +float x[] = { 1.0f, 2.0f, 3.0f, 4.0f }; |
| 199 | +const stdlib_complex64_t alpha = stdlib_complex64( 5.0f, 0.0f ); |
| 200 | + |
| 201 | +stdlib_strided_cxsa( 2, alpha, (stdlib_complex64_t *)x, 1 ); |
| 202 | +``` |
| 203 | +
|
| 204 | +The function accepts the following arguments: |
| 205 | +
|
| 206 | +- **N**: `[in] CBLAS_INT` number of indexed elements. |
| 207 | +- **alpha**: `[in] stdlib_complex64_t` scalar constant. |
| 208 | +- **X**: `[inout] stdlib_complex64_t*` input array. |
| 209 | +- **strideX**: `[in] CBLAS_INT` stride length for `X`. |
| 210 | +
|
| 211 | +```c |
| 212 | +void stdlib_strided_cxsa( const CBLAS_INT N, const stdlib_complex64_t alpha, stdlib_complex64_t *X, const CBLAS_INT strideX ); |
| 213 | +``` |
| 214 | + |
| 215 | +#### stdlib_strided_cxsa_ndarray( N, alpha, \*X, strideX, offsetX ) |
| 216 | + |
| 217 | +Subtracts a scalar constant from each element in a single-precision complex floating-point strided array using alternative indexing semantics. |
| 218 | + |
| 219 | +```c |
| 220 | +#include "stdlib/complex/float32/ctor.h" |
| 221 | + |
| 222 | +float x[] = { 1.0f, 2.0f, 3.0f, 4.0f }; |
| 223 | +const stdlib_complex64_t alpha = stdlib_complex64( 5.0f, 0.0f ); |
| 224 | + |
| 225 | +stdlib_strided_cxsa_ndarray( 2, alpha, (stdlib_complex64_t *)x, 1, 0 ); |
| 226 | +``` |
| 227 | +
|
| 228 | +The function accepts the following arguments: |
| 229 | +
|
| 230 | +- **N**: `[in] CBLAS_INT` number of indexed elements. |
| 231 | +- **alpha**: `[in] stdlib_complex64_t` scalar constant. |
| 232 | +- **X**: `[inout] stdlib_complex64_t*` input array. |
| 233 | +- **strideX**: `[in] CBLAS_INT` stride length for `X`. |
| 234 | +- **offsetX**: `[in] CBLAS_INT` starting index for `X`. |
| 235 | +
|
| 236 | +```c |
| 237 | +void stdlib_strided_cxsa_ndarray( const CBLAS_INT N, const stdlib_complex64_t alpha, stdlib_complex64_t *X, const CBLAS_INT strideX, const CBLAS_INT offsetX ); |
| 238 | +``` |
| 239 | + |
| 240 | +</section> |
| 241 | + |
| 242 | +<!-- /.usage --> |
| 243 | + |
| 244 | +<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 245 | + |
| 246 | +<section class="notes"> |
| 247 | + |
| 248 | +</section> |
| 249 | + |
| 250 | +<!-- /.notes --> |
| 251 | + |
| 252 | +<!-- C API usage examples. --> |
| 253 | + |
| 254 | +<section class="examples"> |
| 255 | + |
| 256 | +### Examples |
| 257 | + |
| 258 | +```c |
| 259 | +#include "stdlib/blas/ext/base/cxsa.h" |
| 260 | +#include "stdlib/complex/float32/ctor.h" |
| 261 | +#include "stdlib/complex/float32/real.h" |
| 262 | +#include "stdlib/complex/float32/imag.h" |
| 263 | +#include <stdio.h> |
| 264 | + |
| 265 | +int main( void ) { |
| 266 | + // Create a strided array: |
| 267 | + stdlib_complex64_t x[] = { |
| 268 | + stdlib_complex64( 1.0f, -2.0f ), |
| 269 | + stdlib_complex64( 3.0f, -4.0f ), |
| 270 | + stdlib_complex64( 5.0f, -6.0f ), |
| 271 | + stdlib_complex64( 7.0f, -8.0f ) |
| 272 | + }; |
| 273 | + |
| 274 | + // Specify the number of indexed elements: |
| 275 | + const int N = 4; |
| 276 | + |
| 277 | + // Specify a stride: |
| 278 | + const int strideX = 1; |
| 279 | + |
| 280 | + // Scalar constant: |
| 281 | + stdlib_complex64_t alpha = stdlib_complex64( 5.0f, 0.0f ); |
| 282 | + |
| 283 | + // Subtract a constant from each element: |
| 284 | + stdlib_strided_cxsa( N, alpha, x, strideX ); |
| 285 | + |
| 286 | + // Print the result: |
| 287 | + for ( int i = 0; i < N; i++ ) { |
| 288 | + printf( "x[ %i ] = %f + %fi\n", i, stdlib_complex64_real( x[ i ] ), stdlib_complex64_imag( x[ i ] ) ); |
| 289 | + } |
| 290 | +} |
| 291 | +``` |
| 292 | +
|
| 293 | +</section> |
| 294 | +
|
| 295 | +<!-- /.examples --> |
| 296 | +
|
| 297 | +</section> |
| 298 | +
|
| 299 | +<!-- /.c --> |
| 300 | +
|
| 301 | +<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. --> |
| 302 | +
|
| 303 | +<section class="related"> |
| 304 | +
|
| 305 | +</section> |
| 306 | +
|
| 307 | +<!-- /.related --> |
| 308 | +
|
| 309 | +<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 310 | +
|
| 311 | +<section class="links"> |
| 312 | +
|
| 313 | +[@stdlib/array/complex64]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/complex64 |
| 314 | +
|
| 315 | +[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray |
| 316 | +
|
| 317 | +<!-- <related-links> --> |
| 318 | +
|
| 319 | +<!-- </related-links> --> |
| 320 | +
|
| 321 | +</section> |
| 322 | +
|
| 323 | +<!-- /.links --> |
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