275 lines
7.0 KiB
Markdown
275 lines
7.0 KiB
Markdown
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<!--
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@license Apache-2.0
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Copyright (c) 2020 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# strunc
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> Round each element in a single-precision floating-point strided array toward zero.
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<section class="intro">
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</section>
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<!-- /.intro -->
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<section class="usage">
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## Usage
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```javascript
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var strunc = require( '@stdlib/math/strided/special/strunc' );
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```
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#### strunc( N, x, strideX, y, strideY )
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Rounds each element in a single-precision floating-point strided array `x` toward zero and assigns the results to elements in a single-precision floating-point strided array `y`.
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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var x = new Float32Array( [ 1.1, 2.5, -3.5, 4.0, -5.9 ] );
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// Perform operation in-place:
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strunc( x.length, x, 1, x, 1 );
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// x => <Float32Array>[ 1.0, 2.0, -3.0, 4.0, -5.0 ]
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```
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The function accepts the following arguments:
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- **N**: number of indexed elements.
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- **x**: input [`Float32Array`][@stdlib/array/float32].
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- **strideX**: index increment for `x`.
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- **y**: output [`Float32Array`][@stdlib/array/float32].
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- **strideY**: index increment for `y`.
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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,
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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var x = new Float32Array( [ 1.1, 2.5, -3.5, 4.0, -5.9, 6.4 ] );
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var y = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
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strunc( 3, x, 2, y, -1 );
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// y => <Float32Array>[ -5.0, -3.0, 1.0, 0.0, 0.0, 0.0 ]
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```
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Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][@stdlib/array/float32] views.
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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// Initial arrays...
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var x0 = new Float32Array( [ 1.1, 2.5, -3.5, 4.0, -5.9, 6.4 ] );
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var y0 = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
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// Create offset views...
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var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
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var y1 = new Float32Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
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strunc( 3, x1, -2, y1, 1 );
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// y0 => <Float32Array>[ 0.0, 0.0, 0.0, 6.0, 4.0, 2.0 ]
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```
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#### strunc.ndarray( N, x, strideX, offsetX, y, strideY, offsetY )
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Rounds each element in a single-precision floating-point strided array `x` toward zero and assigns the results to elements in a single-precision floating-point strided array `y` using alternative indexing semantics.
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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var x = new Float32Array( [ 1.1, 2.5, -3.5, 4.0, -5.9 ] );
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var y = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );
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strunc.ndarray( x.length, x, 1, 0, y, 1, 0 );
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// y => <Float32Array>[ 1.0, 2.0, -3.0, 4.0, -5.0 ]
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```
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The function accepts the following additional arguments:
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- **offsetX**: starting index for `x`.
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- **offsetY**: starting index for `y`.
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While [`typed array`][@stdlib/array/float32] 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`,
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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var x = new Float32Array( [ 1.1, 2.5, -3.5, 4.0, -5.9, 6.4 ] );
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var y = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
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strunc.ndarray( 3, x, 2, 1, y, -1, y.length-1 );
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// y => <Float32Array>[ 0.0, 0.0, 0.0, 6.0, 4.0, 2.0 ]
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```
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</section>
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<!-- /.usage -->
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<section class="notes">
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</section>
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<!-- /.notes -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var uniform = require( '@stdlib/random/base/uniform' );
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var Float32Array = require( '@stdlib/array/float32' );
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var strunc = require( '@stdlib/math/strided/special/strunc' );
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var x = new Float32Array( 10 );
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var y = new Float32Array( 10 );
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var i;
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for ( i = 0; i < x.length; i++ ) {
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x[ i ] = uniform( -10.0, 10.0 );
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}
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console.log( x );
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console.log( y );
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strunc.ndarray( x.length, x, 1, 0, y, -1, y.length-1 );
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console.log( y );
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```
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</section>
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<!-- /.examples -->
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<!-- C interface documentation. -->
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* * *
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<section class="c">
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## C APIs
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<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
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<section class="intro">
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</section>
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<!-- /.intro -->
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<!-- C usage documentation. -->
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<section class="usage">
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### Usage
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```c
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#include "stdlib/math/strided/special/strunc.h"
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```
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#### stdlib_strided_strunc( N, \*X, strideX, \*Y, strideY )
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Rounds each element in a single-precision floating-point strided array `X` toward zero and assigns the results to elements in a single-precision floating-point strided array `Y`.
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```c
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#include <stdint.h>
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float X[] = { 1.1, 2.5, -3.5, 4.0, -5.9, 6.4, -7.0, 8.2 };
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float Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
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int64_t N = 4;
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stdlib_strided_strunc( N, X, 2, Y, 2 );
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```
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The function accepts the following arguments:
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- **N**: `[in] int64_t` number of indexed elements.
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- **X**: `[in] float*` input array.
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- **strideX**: `[in] int64_t` index increment for `X`.
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- **Y**: `[out] float*` output array.
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- **strideY**: `[in] int64_t` index increment for `Y`.
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```c
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void stdlib_strided_strunc( const int64_t N, const float *X, const int64_t strideX, float *Y, const int64_t strideY );
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```
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</section>
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<!-- /.usage -->
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<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="notes">
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</section>
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<!-- /.notes -->
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<!-- C API usage examples. -->
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<section class="examples">
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### Examples
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```c
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#include "stdlib/math/strided/special/strunc.h"
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#include <stdint.h>
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#include <stdio.h>
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int main() {
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// Create an input strided array:
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float X[] = { 1.1, 2.5, -3.5, 4.0, -5.9, 6.4, -7.0, 8.2 };
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// Create an output strided array:
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float Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
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// Specify the number of elements:
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int64_t N = 4;
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// Specify the stride lengths:
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int64_t strideX = 2;
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int64_t strideY = 2;
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// Compute the results:
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stdlib_strided_strunc( N, X, strideX, Y, strideY );
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// Print the results:
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for ( int i = 0; i < 8; i++ ) {
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printf( "Y[ %i ] = %f\n", i, Y[ i ] );
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}
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}
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```
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</section>
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<!-- /.examples -->
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</section>
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<!-- /.c -->
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<section class="links">
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[@stdlib/array/float32]: https://www.npmjs.com/package/@stdlib/array-float32
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</section>
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<!-- /.links -->
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