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Sort a doubleprecision floatingpoint strided array using heapsort.
npm install @stdlib/blasextbasedsorthp
var dsorthp = require( '@stdlib/blasextbasedsorthp' );
Sorts a doubleprecision floatingpoint strided array x
using heapsort.
var Float64Array = require( '@stdlib/arrayfloat64' );
var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0 ] );
dsorthp( x.length, 1.0, x, 1 );
// x => <Float64Array>[ 4.0, 2.0, 1.0, 3.0 ]
The function has the following parameters:
 N: number of indexed elements.

order: sort order. If
order < 0.0
, the input strided array is sorted in decreasing order. Iforder > 0.0
, the input strided array is sorted in increasing order. Iforder == 0.0
, the input strided array is left unchanged. 
x: input
Float64Array
.  stride: index increment.
The N
and stride
parameters determine which elements in x
are accessed at runtime. For example, to sort every other element
var Float64Array = require( '@stdlib/arrayfloat64' );
var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0 ] );
dsorthp( 2, 1.0, x, 2 );
// x => <Float64Array>[ 3.0, 2.0, 1.0, 4.0 ]
Note that indexing is relative to the first index. To introduce an offset, use typed array
views.
var Float64Array = require( '@stdlib/arrayfloat64' );
// Initial array...
var x0 = new Float64Array( [ 1.0, 2.0, 3.0, 4.0 ] );
// Create an offset view...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
// Sort every other element...
dsorthp( 2, 1.0, x1, 2 );
// x0 => <Float64Array>[ 1.0, 4.0, 3.0, 2.0 ]
Sorts a doubleprecision floatingpoint strided array x
using heapsort and alternative indexing semantics.
var Float64Array = require( '@stdlib/arrayfloat64' );
var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0 ] );
dsorthp.ndarray( x.length, 1.0, x, 1, 0 );
// x => <Float64Array>[ 4.0, 2.0, 1.0, 3.0 ]
The function has the following additional parameters:
 offset: starting index.
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 access only the last three elements of x
var Float64Array = require( '@stdlib/arrayfloat64' );
var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
dsorthp.ndarray( 3, 1.0, x, 1, x.length3 );
// x => <Float64Array>[ 1.0, 2.0, 3.0, 6.0, 4.0, 5.0 ]
 If
N <= 0
ororder == 0.0
, both functions returnx
unchanged.  The algorithm distinguishes between
0
and+0
. When sorted in increasing order,0
is sorted before+0
. When sorted in decreasing order,0
is sorted after+0
.  The algorithm sorts
NaN
values to the end. When sorted in increasing order,NaN
values are sorted last. When sorted in decreasing order,NaN
values are sorted first.  The algorithm has space complexity
O(1)
and time complexityO(N log2 N)
.  The algorithm is unstable, meaning that the algorithm may change the order of strided array elements which are equal or equivalent (e.g.,
NaN
values).  The input strided array is sorted inplace (i.e., the input strided array is mutated).
var round = require( '@stdlib/mathbasespecialround' );
var randu = require( '@stdlib/randombaserandu' );
var Float64Array = require( '@stdlib/arrayfloat64' );
var dsorthp = require( '@stdlib/blasextbasedsorthp' );
var rand;
var sign;
var x;
var i;
x = new Float64Array( 10 );
for ( i = 0; i < x.length; i++ ) {
rand = round( randu()*100.0 );
sign = randu();
if ( sign < 0.5 ) {
sign = 1.0;
} else {
sign = 1.0;
}
x[ i ] = sign * rand;
}
console.log( x );
dsorthp( x.length, 1.0, x, 1 );
console.log( x );
 Williams, John William Joseph. 1964. "Algorithm 232: Heapsort." Communications of the ACM 7 (6). New York, NY, USA: Association for Computing Machinery: 347–49. doi:10.1145/512274.512284.
 Floyd, Robert W. 1964. "Algorithm 245: Treesort." Communications of the ACM 7 (12). New York, NY, USA: Association for Computing Machinery: 701. doi:10.1145/355588.365103.

@stdlib/blasext/base/dsort2hp
: simultaneously sort two doubleprecision floatingpoint strided arrays based on the sort order of the first array using heapsort. 
@stdlib/blasext/base/gsorthp
: sort a strided array using heapsort. 
@stdlib/blasext/base/ssorthp
: sort a singleprecision floatingpoint strided array using heapsort.
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For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
See LICENSE.
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