time-to-botec

README.md (7803B)

---

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 # dabs
 
 > Compute the [absolute value][@stdlib/math/base/special/abs] for each element in a double-precision floating-point strided array.
 
 <section class="intro">
 
 </section>
 
 <!-- /.intro -->
 
 <section class="usage">
 
 ## Usage
 
 ```javascript
 var dabs = require( '@stdlib/math/strided/special/dabs' );
 ```
 
 #### dabs( N, x, strideX, y, strideY )
 
 Computes the [absolute value][@stdlib/math/base/special/abs] for each element in a double-precision floating-point strided array `x` and assigns the results to elements in a double-precision floating-point strided array `y`.
 
 ```javascript
 var Float64Array = require( '@stdlib/array/float64' );
 
 var x = new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );
 
 // Compute the absolute values in-place:
 dabs( x.length, x, 1, x, 1 );
 // x => <Float64Array>[ 2.0, 1.0, 3.0, 5.0, 4.0, 0.0, 1.0, 3.0 ]
 ```
 
 The function accepts the following arguments:
 
 -   **N**: number of indexed elements.
 -   **x**: input [`Float64Array`][@stdlib/array/float64].
 -   **strideX**: index increment for `x`.
 -   **y**: output [`Float64Array`][@stdlib/array/float64].
 -   **strideY**: index increment for `y`.
 
 The `N` and `stride` parameters determine which elements in `x` and `y` are accessed at runtime. For example, to index every other value in `x` and to index the first `N` elements of `y` in reverse order,
 
 ```javascript
 var Float64Array = require( '@stdlib/array/float64' );
 var floor = require( '@stdlib/math/base/special/floor' );
 
 var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
 var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
 
 var N = floor( x.length / 2 );
 
 dabs( N, x, 2, y, -1 );
 // y => <Float64Array>[ 5.0, 3.0, 1.0, 0.0, 0.0, 0.0 ]
 ```
 
 Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][@stdlib/array/float64] views.
 
 ```javascript
 var Float64Array = require( '@stdlib/array/float64' );
 var floor = require( '@stdlib/math/base/special/floor' );
 
 // Initial arrays...
 var x0 = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
 var y0 = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
 
 // Create offset views...
 var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
 var y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
 
 var N = floor( x0.length / 2 );
 
 dabs( N, x1, -2, y1, 1 );
 // y0 => <Float64Array>[ 0.0, 0.0, 0.0, 6.0, 4.0, 2.0 ]
 ```
 
 #### dabs.ndarray( N, x, strideX, offsetX, y, strideY, offsetY )
 
 Computes the [absolute value][@stdlib/math/base/special/abs] for each element in a double-precision floating-point strided array `x` and assigns the results to elements in a double-precision floating-point strided array `y` using alternative indexing semantics.
 
 ```javascript
 var Float64Array = require( '@stdlib/array/float64' );
 
 var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0 ] );
 var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );
 
 dabs.ndarray( x.length, x, 1, 0, y, 1, 0 );
 // y => <Float64Array>[ 1.0, 2.0, 3.0, 4.0, 5.0 ]
 ```
 
 The function accepts the following additional arguments:
 
 -   **offsetX**: starting index for `x`.
 -   **offsetY**: starting index for `y`.
 
 While [`typed array`][@stdlib/array/float64] views mandate a view offset based on the underlying `buffer`, the `offsetX` and `offsetY` parameters support indexing semantics based on starting indices. For example, to index every other value in `x` starting from the second value and to index the last `N` elements in `y`,
 
 ```javascript
 var Float64Array = require( '@stdlib/array/float64' );
 var floor = require( '@stdlib/math/base/special/floor' );
 
 var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
 var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
 
 var N = floor( x.length / 2 );
 
 dabs.ndarray( N, x, 2, 1, y, -1, y.length-1 );
 // y => <Float64Array>[ 0.0, 0.0, 0.0, 6.0, 4.0, 2.0 ]
 ```
 
 </section>
 
 <!-- /.usage -->
 
 <section class="notes">
 
 </section>
 
 <!-- /.notes -->
 
 <section class="examples">
 
 ## Examples
 
 <!-- eslint no-undef: "error" -->
 
 ```javascript
 var round = require( '@stdlib/math/base/special/round' );
 var randu = require( '@stdlib/random/base/randu' );
 var Float64Array = require( '@stdlib/array/float64' );
 var dabs = require( '@stdlib/math/strided/special/dabs' );
 
 var x = new Float64Array( 10 );
 var y = new Float64Array( 10 );
 
 var i;
 for ( i = 0; i < x.length; i++ ) {
     x[ i ] = round( (randu()*200.0) - 100.0 );
 }
 console.log( x );
 console.log( y );
 
 dabs.ndarray( x.length, x, 1, 0, y, -1, y.length-1 );
 console.log( y );
 ```
 
 </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/math/strided/special/dabs.h"
 ```
 
 #### stdlib_strided_dabs( N, \*X, strideX, \*Y, strideY )
 
 Computes the absolute value for each element in a double-precision floating-point strided array `X` and assigns the results to elements in a double-precision floating-point strided array `Y`.
 
 ```c
 #include <stdint.h>
 
 double X[] = { -1.0, -2.0, -3.0, -4.0, -5.0, -6.0, -7.0, -8.0 };
 double Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
 
 int64_t N = 4;
 
 stdlib_strided_dabs( N, X, 2, Y, 2 );
 ```
 
 The function accepts the following arguments:
 
 -   **N**: `[in] int64_t` number of indexed elements.
 -   **X**: `[in] double*` input array.
 -   **strideX**: `[in] int64_t` index increment for `X`.
 -   **Y**: `[out] double*` output array.
 -   **strideY**: `[in] int64_t` index increment for `Y`.
 
 ```c
 void stdlib_strided_dabs( const int64_t N, const double *X, const int64_t strideX, double *Y, const int64_t strideY );
 ```
 
 </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/math/strided/special/dabs.h"
 #include <stdint.h>
 #include <stdio.h>
 
 int main() {
     // Create an input strided array:
     double X[] = { -1.0, -2.0, -3.0, -4.0, -5.0, -6.0, -7.0, -8.0 };
 
     // Create an output strided array:
     double Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
 
     // Specify the number of elements:
     int64_t N = 4;
 
     // Specify the stride lengths:
     int64_t strideX = 2;
     int64_t strideY = 2;
 
     // Compute the absolute value element-wise:
     stdlib_strided_dabs( N, X, strideX, Y, strideY );
 
     // Print the result:
     for ( int i = 0; i < 8; i++ ) {
         printf( "Y[ %i ] = %lf\n", i, Y[ i ] );
     }
 }
 ```
 
 </section>
 
 <!-- /.examples -->
 
 </section>
 
 <!-- /.c -->
 
 <section class="links">
 
 [@stdlib/array/float64]: https://www.npmjs.com/package/@stdlib/array-float64
 
 [@stdlib/math/base/special/abs]: https://www.npmjs.com/package/@stdlib/math/tree/main/base/special/abs
 
 </section>
 
 <!-- /.links -->