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README.md

clacgv

Conjugate each element in a single-precision complex floating-point vector.

Usage

var clacgv = require( '@stdlib/lapack/base/clacgv' );

clacgv( N, cx, strideCX )

Conjugates each element in a single-precision complex floating-point vector.

var Complex64Array = require( '@stdlib/array/complex64' );

var cx = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0 ] );

clacgv( 2, cx, 1 );

var z = cx.get( 0 );
// returns <Complex64>[ 1.0, -2.0 ]

The function has the following parameters:

  • N: number of indexed elements.
  • cx: input Complex64Array.
  • strideCX: stride length for cx.

The N and stride parameters determine which elements in cx are conjugated. For example, to conjugate every other element in cx,

var Complex64Array = require( '@stdlib/array/complex64' );

var cx = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );

clacgv( 2, cx, 2 );

var z = cx.get( 0 );
// returns <Complex64>[ 1.0, -2.0 ]

Note that indexing is relative to the first index. To introduce an offset, use typed array views.

var Complex64Array = require( '@stdlib/array/complex64' );
var Complex64 = require( '@stdlib/complex/float32/ctor' );

// Initial array:
var cx0 = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );

// Create an offset view:
var cx1 = new Complex64Array( cx0.buffer, cx0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

// Conjugate every element in `cx1`:
clacgv( 3, cx1, 1 );

var z = cx0.get( 1 );
// returns <Complex64>[ 3.0, -4.0 ]

clacgv.ndarray( N, cx, strideCX, offsetCX )

Conjugates each element in a single-precision floating-point vector using alternative indexing semantics.

var Complex64Array = require( '@stdlib/array/complex64' );

var cx = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );

clacgv.ndarray( 3, cx, 1, 0 );

var z = cx.get( 0 );
// returns <Complex64>[ 1.0, -2.0 ]

The function has the following additional parameters:

  • offsetCX: starting index for cx.

While typed array views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index. For example, to conjugate every other element in the input strided array starting from the second element,

var Complex64Array = require( '@stdlib/array/complex64' );

var cx = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );

clacgv.ndarray( 2, cx, 2, 1 );

var z = cx.get( 3 );
// returns <Complex64>[ 7.0, -8.0 ]

Notes

  • If N <= 0, both functions return cx unchanged.
  • clacgv() corresponds to the LAPACK BLAS-like level 1 routine clacgv.

Examples

var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
var filledarrayBy = require( '@stdlib/array/filled-by' );
var Complex64 = require( '@stdlib/complex/float32/ctor' );
var clacgv = require( '@stdlib/lapack/base/clacgv' );

function rand() {
    return new Complex64( discreteUniform( 0, 10 ), discreteUniform( -5, 5 ) );
}

var cx = filledarrayBy( 10, 'complex64', rand );
console.log( cx.toString() );

// Conjugate elements:
clacgv( cx.length, cx, 1 );
console.log( cx.get( cx.length-1 ).toString() );