dcopy
Copy values from
x
intoy
.
Usage
var dcopy = require( '@stdlib/blas/base/dcopy' );
dcopy( N, x, strideX, y, strideY )
Copies values from x
into y
.
var Float64Array = require( '@stdlib/array/float64' );
var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float64Array( [ 6.0, 7.0, 8.0, 9.0, 10.0 ] );
dcopy( x.length, x, 1, y, 1 );
// y => <Float64Array>[ 1.0, 2.0, 3.0, 4.0, 5.0 ]
The function has the following parameters:
- N: number of values to copy.
- x: input
Float64Array
. - strideX: index increment for
x
. - y: destination
Float64Array
. - strideY: index increment for
y
.
The N
and stride
parameters determine how values from x
are copied into y
. For example, to copy in reverse order every other value in x
into the first N
elements of y
,
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( [ 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
var N = floor( x.length / 2 );
dcopy( N, x, -2, y, 1 );
// y => <Float64Array>[ 5.0, 3.0, 1.0, 10.0, 11.0, 12.0 ]
Note that indexing is relative to the first index. To introduce an offset, use typed array
views.
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( [ 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
// 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 );
// Copy in reverse order every other value from `x1` into `y1`...
dcopy( N, x1, -2, y1, 1 );
// y0 => <Float64Array>[ 7.0, 8.0, 9.0, 6.0, 4.0, 2.0 ]
dcopy.ndarray( N, x, strideX, offsetX, y, strideY, offsetY )
Copies values from x
into y
using alternative indexing semantics.
var Float64Array = require( '@stdlib/array/float64' );
var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float64Array( [ 6.0, 7.0, 8.0, 9.0, 10.0 ] );
dcopy.ndarray( x.length, x, 1, 0, y, 1, 0 );
// y => <Float64Array>[ 1.0, 2.0, 3.0, 4.0, 5.0 ]
The function has the following additional parameters:
- offsetX: starting index for
x
. - offsetY: starting index for
y
.
While typed array
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 copy every other value in x
starting from the second value into the last N
elements in y
where x[i] = y[n]
, x[i+2] = y[n-1]
,...,
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( [ 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
var N = floor( x.length / 2 );
dcopy.ndarray( N, x, 2, 1, y, -1, y.length-1 );
// y => <Float64Array>[ 7.0, 8.0, 9.0, 6.0, 4.0, 2.0 ]
Notes
Examples
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var Float64Array = require( '@stdlib/array/float64' );
var dcopy = require( '@stdlib/blas/base/dcopy' );
var x;
var y;
var i;
x = new Float64Array( 10 );
y = new Float64Array( 10 );
for ( i = 0; i < x.length; i++ ) {
x[ i ] = round( randu()*500.0 );
y[ i ] = round( randu()*255.0 );
}
console.log( x );
console.log( y );
// Copy elements from `x` into `y` starting from the end of `y`:
dcopy( x.length, x, 1, y, -1 );
console.log( y );