Determine the index offset which specifies the location of the first indexed value in a strided array.
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> Determine the index offset which specifies the location of the first indexed value in a strided array.
``bash`
npm install @stdlib/strided-base-stride2offset
`javascript`
var stride2offset = require( '@stdlib/strided-base-stride2offset' );
#### stride2offset( N, stride )
Returns the index offset which specifies the location of the first indexed value in a strided array.
`javascript
var offset = stride2offset( 10, 10 );
// returns 0
offset = stride2offset( 10, -10 );
// returns 90
`
`javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var stride2offset = require( '@stdlib/strided-base-stride2offset' );
var opts = {
'dtype': 'generic'
};
// Define the number of indexed elements:
var N = 100;
// Define a maximum stride length:
var maxStride = 10;
// Create an array of random integers which can accommodate the maximum stride length:
var arr = discreteUniform( N*maxStride, 0, 255, opts );
// Generate random stride lengths:
var strides = discreteUniform( 10, -maxStride, maxStride, opts );
// Resolve values in the data array for the first indexed element based on various stride lengths...
var offset;
var i;
for ( i = 0; i < strides.length; i++ ) {
offset = stride2offset( N, strides[ i ] );
console.log( 'stride = %d. arr[%d] = %d.', strides[ i ], offset, arr[ offset ] );
}
`
*
`c`
#include "stdlib/strided/base/stride2offset.h"
#### stdlib_strided_stride2offset( N, stride )
Returns the index offset which specifies the location of the first indexed value in a strided array.
`c
#include "stdlib/strided/base/stride2offset.h"
#include
int64_t offset = stdlib_strided_stride2offset( 10, -10 );
// returns 90
`
The function accepts the following arguments:
- N: [in] int64_t number of indexed elements.[in] int64_t
- stride: index increment.
`c`
int64_t stdlib_strided_stride2offset( int64_t N, int64_t stride );
`c
#include "stdlib/strided/base/stride2offset.h"
#include
#include
#include
int main( void ) {
// Specify the number of indexed elements:
int64_t N = 6;
// Define a stride:
int64_t stride = -2;
// Compute the offset:
int64_t offset = stdlib_strided_stride2offset( N, stride )
// Print the results:
printf( "stride: %"PRId64" => offset: %"PRId64"\n", stride, offset );
}
`
*
This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].
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