feat: add blas/ext/base/zfirst-index-less-than

lib/node_modules/@stdlib/blas/ext/base/zfirst-index-less-than/README.md

@@ -0,0 +1,365 @@
+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2026 The Stdlib Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+-->
+
+# zfirstIndexLessThan
+
+> Return the index of the first element in a double-precision complex floating-point strided array which is less than a corresponding element in another double-precision complex floating-point strided array.
+
+<!-- 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 -->
+
+<!-- Package usage documentation. -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var zfirstIndexLessThan = require( '@stdlib/blas/ext/base/zfirst-index-less-than' );
+```
+
+#### zfirstIndexLessThan( N, x, strideX, y, strideY )
+
+Returns the index of the first element in a double-precision complex floating-point strided array which is less than a corresponding element in another double-precision complex floating-point strided array.
+
+```javascript
+var Complex128Array = require( '@stdlib/array/complex128' );
+
+var x = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
+var y = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 0.0, 0.0 ] );
+
+var idx = zfirstIndexLessThan( x.length, x, 1, y, 1 );
+// returns 2
+```
+
+The function has the following parameters:
+
+-   **N**: number of indexed elements.
+-   **x**: first input [`Complex128Array`][@stdlib/array/complex128].
+-   **strideX**: stride length for `x`.
+-   **y**: second input [`Complex128Array`][@stdlib/array/complex128].
+-   **strideY**: stride length for `y`.
+
+If the function is unable to find an element in `x` which is less than a corresponding element in `y`, the function returns `-1`.
+
+```javascript
+var Complex128Array = require( '@stdlib/array/complex128' );
+
+var x = new Complex128Array( [ 5.0, 5.0, 6.0, 6.0, 7.0, 7.0, 8.0, 8.0 ] );
+var y = new Complex128Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0, 4.0, 4.0 ] );
+
+var idx = zfirstIndexLessThan( x.length, x, 1, y, 1 );
+// returns -1
+```
+
+The `N` and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to compare every other element:
+
+<!-- eslint-disable max-len -->
+
+```javascript
+var Complex128Array = require( '@stdlib/array/complex128' );
+
+var x = new Complex128Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0, 4.0, 4.0, 5.0, 5.0, 6.0, 6.0 ] );
+var y = new Complex128Array( [ 0.0, 0.0, 9.0, 9.0, 0.0, 0.0, 9.0, 9.0, 9.0, 9.0, 9.0, 9.0 ] );
+
+var idx = zfirstIndexLessThan( 3, x, 2, y, 2 );
+// returns 2
+```
+
+Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.
+
+```javascript
+var Complex128Array = require( '@stdlib/array/complex128' );
+
+// Initial arrays...
+var x0 = new Complex128Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0, 4.0, 4.0 ] );
+var y0 = new Complex128Array( [ 9.0, 9.0, 0.0, 0.0, 9.0, 9.0, 9.0, 9.0 ] );
+
+// Create offset views...
+var x1 = new Complex128Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
+var y1 = new Complex128Array( y0.buffer, y0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
+
+// Find index...
+var idx = zfirstIndexLessThan( 2, x1, 1, y1, 1 );
+// returns 1
+```
+
+<!-- lint disable maximum-heading-length -->
+
+#### zfirstIndexLessThan.ndarray( N, x, strideX, offsetX, y, strideY, offsetY )
+
+<!-- lint enable maximum-heading-length -->
+
+Returns the index of the first element in a double-precision complex floating-point strided array which is less than a corresponding element in another double-precision complex floating-point strided array using alternative indexing semantics.
+
+```javascript
+var Complex128Array = require( '@stdlib/array/complex128' );
+
+var x = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
+var y = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 0.0, 0.0 ] );
+
+var idx = zfirstIndexLessThan.ndarray( x.length, x, 1, 0, y, 1, 0 );
+// returns 2
+```
+
+The function has the following additional parameters:
+
+-   **offsetX**: starting index for `x`.
+-   **offsetY**: starting index for `y`.
+
+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 three elements of each strided array:
+
+<!-- eslint-disable max-len -->
+
+```javascript
+var Complex128Array = require( '@stdlib/array/complex128' );
+
+var x = new Complex128Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0, 4.0, 4.0, 5.0, 5.0, 6.0, 6.0 ] );
+var y = new Complex128Array( [ 9.0, 9.0, 9.0, 9.0, 9.0, 9.0, 0.0, 0.0, 9.0, 9.0, 9.0, 9.0 ] );
+
+var idx = zfirstIndexLessThan.ndarray( 3, x, 1, x.length-3, y, 1, y.length-3 );
+// returns 1
+```
+
+</section>
+
+<!-- /.usage -->
+
+<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+## Notes
+
+-   When comparing elements, the function checks whether both the real and imaginary components of an element in `x` are less than the corresponding real and imaginary components of an element in `y` using the less-than operator `<`. As a consequence, comparisons involving `NaN` always evaluate to `false`.
+
+</section>
+
+<!-- /.notes -->
+
+<!-- Package usage examples. -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var uniform = require( '@stdlib/random/array/uniform' );
+var Complex128Array = require( '@stdlib/array/complex128' );
+var logEach = require( '@stdlib/console/log-each' );
+var zfirstIndexLessThan = require( '@stdlib/blas/ext/base/zfirst-index-less-than' );
+
+var xbuf = uniform( 10*2, -10.0, 10.0, {
+    'dtype': 'float64'
+});
+var x = new Complex128Array( xbuf.buffer );
+logEach( '%s', x );
+
+var ybuf = uniform( 10*2, -10.0, 10.0, {
+    'dtype': 'float64'
+});
+var y = new Complex128Array( ybuf.buffer );
+logEach( '%s', y );
+
+var idx = zfirstIndexLessThan( x.length, x, 1, y, 1 );
+console.log( idx );
+```
+
+</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/blas/ext/base/zfirst_index_less_than.h"
+```
+
+<!-- lint disable maximum-heading-length -->
+
+#### stdlib_strided_zfirst_index_less_than( N, \*X, strideX, \*Y, strideY )
+
+<!-- lint enable maximum-heading-length -->
+
+Returns the index of the first element in a double-precision complex floating-point strided array which is less than a corresponding element in another double-precision complex floating-point strided array.
+
+```c
+#include "stdlib/complex/float64/ctor.h"
+
+const double x[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
+const double y[] = { 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 0.0, 0.0 };
+
+int idx = stdlib_strided_zfirst_index_less_than( 4, (const stdlib_complex128_t *)x, 1, (const stdlib_complex128_t *)y, 1 );
+// returns 2
+```
+
+The function accepts the following arguments:
+
+-   **N**: `[in] CBLAS_INT` number of indexed elements.
+-   **X**: `[in] stdlib_complex128_t*` first input array.
+-   **strideX**: `[in] CBLAS_INT` stride length for `X`.
+-   **Y**: `[in] stdlib_complex128_t*` second input array.
+-   **strideY**: `[in] CBLAS_INT` stride length for `Y`.
+
+```c
+CBLAS_INT stdlib_strided_zfirst_index_less_than( const CBLAS_INT N, const stdlib_complex128_t *X, const CBLAS_INT strideX, const stdlib_complex128_t *Y, const CBLAS_INT strideY );
+```
+
+<!-- lint disable maximum-heading-length -->
+
+#### stdlib_strided_zfirst_index_less_than_ndarray( N, \*X, strideX, offsetX, \*Y, strideY, offsetY )
+
+<!-- lint enable maximum-heading-length -->
+
+Returns the index of the first element in a double-precision complex floating-point strided array which is less than a corresponding element in another double-precision complex floating-point strided array using alternative indexing semantics.
+
+```c
+#include "stdlib/complex/float64/ctor.h"
+
+const double x[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
+const double y[] = { 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 0.0, 0.0 };
+
+int idx = stdlib_strided_zfirst_index_less_than_ndarray( 4, (const stdlib_complex128_t *)x, 1, 0, (const stdlib_complex128_t *)y, 1, 0 );
+// returns 2
+```
+
+The function accepts the following arguments:
+
+-   **N**: `[in] CBLAS_INT` number of indexed elements.
+-   **X**: `[in] stdlib_complex128_t*` first input array.
+-   **strideX**: `[in] CBLAS_INT` stride length for `X`.
+-   **offsetX**: `[in] CBLAS_INT` starting index for `X`.
+-   **Y**: `[in] stdlib_complex128_t*` second input array.
+-   **strideY**: `[in] CBLAS_INT` stride length for `Y`.
+-   **offsetY**: `[in] CBLAS_INT` starting index for `Y`.
+
+```c
+CBLAS_INT stdlib_strided_zfirst_index_less_than_ndarray( const CBLAS_INT N, const stdlib_complex128_t *X, const CBLAS_INT strideX, const CBLAS_INT offsetX, const stdlib_complex128_t *Y, const CBLAS_INT strideY, const CBLAS_INT offsetY );
+```
+
+</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">
+
+### Notes
+
+-   When comparing elements, both functions check whether both the real and imaginary components of an element in `X` are less than the corresponding real and imaginary components of an element in `Y` using the less-than operator `<`. As a consequence, comparisons involving `NaN` always evaluate to `false`.
+
+</section>
+
+<!-- /.notes -->
+
+<!-- C API usage examples. -->
+
+<section class="examples">
+
+### Examples
+
+```c
+#include "stdlib/blas/ext/base/zfirst_index_less_than.h"
+#include "stdlib/complex/float64/ctor.h"
+#include <stdio.h>
+
+int main( void ) {
+    // Create strided arrays (interleaved real and imaginary components):
+    const double x[] = { 1.0, 1.0, 1.0, 1.0, 0.0, 0.0, 1.0, 1.0 };
+    const double y[] = { 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 };
+
+    // Specify the number of indexed elements:
+    const int N = 4;
+
+    // Specify stride lengths:
+    const int strideX = 1;
+    const int strideY = 1;
+
+    // Perform a search:
+    int idx = stdlib_strided_zfirst_index_less_than( N, (const stdlib_complex128_t *)x, strideX, (const stdlib_complex128_t *)y, strideY );
+
+    // Print the result:
+    printf( "index value: %d\n", idx );
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
+<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="references">
+
+</section>
+
+<!-- /.references -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+</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/complex128]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/complex128
+
+[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
+
+</section>
+
+<!-- /.links -->