Usage

`javascript
var zswap = require( '@stdlib/blas-base-wasm-zswap' );
`

#### zswap.main( N, x, strideX, y, strideY )

Interchanges two complex double-precision floating-point vectors.

`javascript
var Complex128Array = require( '@stdlib/array-complex128' );

var x = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

zswap.main( x.length, x, 1, y, 1 );
// x => [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ]
// y => [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ]
`

The function has the following parameters:

- N: number of indexed elements.
- x: first input [Complex128Array][@stdlib/array/complex128].
- strideX: index increment for x.
- y: second input [Complex128Array][@stdlib/array/complex128].
- strideY: index increment for y.

The N and stride parameters determine how values from x are interchanged with values from y. For example, to interchange every other value in x with the first N elements of y in reverse order,

`javascript
var Complex128Array = require( '@stdlib/array-complex128' );

var x = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var y = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

zswap.main( 2, x, -2, y, 1 );
// x => [ 0.0, 0.0, 3.0, 4.0, 0.0, 0.0, 7.0, 8.0 ]
// y => [ 5.0, 6.0, 1.0, 2.0, 0.0, 0.0, 0.0, 0.0 ]
`

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, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var y0 = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// 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*2 ); // start at 3rd element

// Interchange every other value from x1 into y1 in reverse order...
zswap.main( 2, x1, -2, y1, 1 );
// x0 => [ 1.0, 2.0, 0.0, 0.0, 5.0, 6.0, 0.0, 0.0 ]
// y0 => [ 0.0, 0.0, 0.0, 0.0, 7.0, 8.0, 3.0, 4.0 ]
`

#### zswap.ndarray( N, x, strideX, offsetX, y, strideY, offsetY )

Interchanges two complex double-precision floating-point vectors using alternative indexing semantics.

`javascript
var Complex128Array = require( '@stdlib/array-complex128' );

var x = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

zswap.ndarray( x.length, x, 1, 0, y, 1, 0 );
// x => [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ]
// y => [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ]
`

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 interchange 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],...,

`javascript
var Complex128Array = require( '@stdlib/array-complex128' );

var x = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var y = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

zswap.ndarray( 2, x, 2, 1, y, -1, y.length-1 );
// x => [ 1.0, 2.0, 0.0, 0.0, 5.0, 6.0, 0.0, 0.0 ]
// y => [ 0.0, 0.0, 0.0, 0.0, 7.0, 8.0, 3.0, 4.0 ]
`

*

$3

#### zswap.Module( memory )

Returns a new WebAssembly [module wrapper][@stdlib/wasm/module-wrapper] instance which uses the provided WebAssembly [memory][@stdlib/wasm/memory] instance as its underlying memory.

`javascript
var Memory = require( '@stdlib/wasm-memory' );

// Create a new memory instance with an initial size of 10 pages (640KiB) and a maximum size of 100 pages (6.4MiB):
var mem = new Memory({
'initial': 10,
'maximum': 100
});

// Create a BLAS routine:
var mod = new zswap.Module( mem );
// returns

// Initialize the routine:
mod.initializeSync();
`

#### zswap.Module.prototype.main( N, xp, sx, yp, sy )

Interchanges two complex double-precision floating-point vectors.

`javascript
var Memory = require( '@stdlib/wasm-memory' );
var oneTo = require( '@stdlib/array-one-to' );
var zeros = require( '@stdlib/array-zeros' );
var bytesPerElement = require( '@stdlib/ndarray-base-bytes-per-element' );
var Complex128Array = require( '@stdlib/array-complex128' );
var reinterpretComplex128 = require( '@stdlib/strided-base-reinterpret-complex128' );
var zswap = require( '@stdlib/blas-base-wasm-zswap' );

// Create a new memory instance with an initial size of 10 pages (320KiB) and a maximum size of 100 pages (6.4MiB):
var mem = new Memory({
'initial': 10,
'maximum': 100
});

// Create a BLAS routine:
var mod = new zswap.Module( mem );
// returns

// Initialize the routine:
mod.initializeSync();

// Define a vector data type:
var dtype = 'complex128';

// Specify a vector length:
var N = 5;

// Define pointers (i.e., byte offsets) for storing input vectors:
var xptr = 0;
var yptr = N * bytesPerElement( dtype );

// Write vector values to module memory:
var xbuf = oneTo( N*2, 'float64' );
var x = new Complex128Array( xbuf.buffer );
mod.write( xptr, x );

var ybuf = zeros( N*2, 'float64' );
var y = new Complex128Array( ybuf.buffer );
mod.write( yptr, y );

// Perform computation:
mod.main( N, xptr, 1, yptr, 1 );

// Read out the results:
var viewX = zeros( N, dtype );
var viewY = zeros( N, dtype );
mod.read( xptr, viewX );
mod.read( yptr, viewY );

console.log( reinterpretComplex128( viewX, 0 ) );
// => [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ]

console.log( reinterpretComplex128( viewY, 0 ) );
// => [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0 ]
`

The function has the following parameters:

- N: number of indexed elements.
- xp: first input [Complex128Array][@stdlib/array/complex128] pointer (i.e., byte offset).
- sx: index increment for x.
- yp: second input [Complex128Array][@stdlib/array/complex128] pointer (i.e., byte offset).
- sy: index increment for y.

#### zswap.Module.prototype.ndarray( N, xp, sx, ox, yp, sy, oy )

Interchanges two complex double-precision floating-point vectors using alternative indexing semantics.

`javascript
var Memory = require( '@stdlib/wasm-memory' );
var oneTo = require( '@stdlib/array-one-to' );
var zeros = require( '@stdlib/array-zeros' );
var bytesPerElement = require( '@stdlib/ndarray-base-bytes-per-element' );
var Complex128Array = require( '@stdlib/array-complex128' );
var reinterpretComplex128 = require( '@stdlib/strided-base-reinterpret-complex128' );
var zswap = require( '@stdlib/blas-base-wasm-zswap' );

// Create a new memory instance with an initial size of 10 pages (320KiB) and a maximum size of 100 pages (6.4MiB):
var mem = new Memory({
'initial': 10,
'maximum': 100
});

// Create a BLAS routine:
var mod = new zswap.Module( mem );
// returns

// Initialize the routine:
mod.initializeSync();

// Define a vector data type:
var dtype = 'complex128';

// Specify a vector length:
var N = 5;

// Define pointers (i.e., byte offsets) for storing input vectors:
var xptr = 0;
var yptr = N * bytesPerElement( dtype );

// Write vector values to module memory:
var xbuf = oneTo( N*2, 'float64' );
var x = new Complex128Array( xbuf.buffer );
mod.write( xptr, x );

var ybuf = zeros( N*2, 'float64' );
var y = new Complex128Array( ybuf.buffer );
mod.write( yptr, y );

// Perform computation:
mod.ndarray( N, xptr, 1, 0, yptr, 1, 0 );

// Read out the results:
var viewX = zeros( N, dtype );
var viewY = zeros( N, dtype );
mod.read( xptr, viewX );
mod.read( yptr, viewY );

console.log( reinterpretComplex128( viewX, 0 ) );
// => [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ]

console.log( reinterpretComplex128( viewY, 0 ) );
// => [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0 ]
`

The function has the following additional parameters:

- ox: starting index for x.
- oy: starting index for y.