Usage

`javascript
var sdsapxsumpw = require( '@stdlib/blas-ext-base-sdsapxsumpw' );
`

#### sdsapxsumpw( N, alpha, x, strideX )

Adds a scalar constant to each single-precision floating-point strided array element and computes the sum using pairwise summation with extended accumulation.

`javascript
var Float32Array = require( '@stdlib/array-float32' );

var x = new Float32Array( [ 1.0, -2.0, 2.0 ] );

var v = sdsapxsumpw( x.length, 5.0, x, 1 );
// returns 16.0
`

The function has the following parameters:

- N: number of indexed elements.
- alpha: scalar constant.
- x: input [Float32Array][@stdlib/array/float32].
- strideX: stride length.

The N and stride parameters determine which elements in the strided array are accessed at runtime. For example, to compute the sum of every other element:

`javascript
var Float32Array = require( '@stdlib/array-float32' );

var x = new Float32Array( [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0 ] );

var v = sdsapxsumpw( 4, 5.0, x, 2 );
// returns 25.0
`

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

`javascript
var Float32Array = require( '@stdlib/array-float32' );

var x0 = new Float32Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );
var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var v = sdsapxsumpw( 4, 5.0, x1, 2 );
// returns 25.0
`

#### sdsapxsumpw.ndarray( N, alpha, x, strideX, offsetX )

Adds a scalar constant to each single-precision floating-point strided array element and computes the sum using pairwise summation with extended accumulation and alternative indexing semantics.

`javascript
var Float32Array = require( '@stdlib/array-float32' );

var x = new Float32Array( [ 1.0, -2.0, 2.0 ] );

var v = sdsapxsumpw.ndarray( x.length, 5.0, x, 1, 0 );
// returns 16.0
`

The function has the following additional parameters:

- offsetX: starting index for x.

While [typed array][mdn-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 every other element starting from the second element:

`javascript
var Float32Array = require( '@stdlib/array-float32' );

var x = new Float32Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );

var v = sdsapxsumpw.ndarray( 4, 5.0, x, 2, 1 );
// returns 25.0
`