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# gnansumpw

> Compute the sum of a one-dimensional ndarray, ignoring `NaN` values and using pairwise summation.

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<section class="usage">

## Usage

```javascript
var gnansumpw = require( '@stdlib/blas/ext/base/ndarray/gnansumpw' );
```

#### gnansumpw( arrays )

Computes the sum of a one-dimensional ndarray, ignoring `NaN` values and using pairwise summation.

```javascript
var vector = require( '@stdlib/ndarray/vector/ctor' );

var x = vector( [ 1.0, -2.0, NaN, 2.0 ], 'generic' );

var v = gnansumpw( [ x ] );
// returns 1.0
```

The function has the following parameters:

-   **arrays**: array-like object containing a one-dimensional input ndarray.

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<section class="notes">

## Notes

-   If provided an empty one-dimensional ndarray, the function returns `0.0`.
-   In general, pairwise summation is more numerically stable than ordinary recursive summation (i.e., "simple" summation), with slightly worse performance. While not the most numerically stable summation technique (e.g., compensated summation techniques such as the Kahan–Babuška-Neumaier algorithm are generally more numerically stable), pairwise summation strikes a reasonable balance between numerical stability and performance. If either numerical stability or performance is more desirable for your use case, consider alternative summation techniques.

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<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var discreteUniform = require( '@stdlib/random/discrete-uniform' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );
var gnansumpw = require( '@stdlib/blas/ext/base/ndarray/gnansumpw' );

var opts = {
    'dtype': 'generic'
};

var x = discreteUniform( [ 10 ], -50, 50, opts );
console.log( ndarray2array( x ) );

var v = gnansumpw( [ x ] );
console.log( v );
```

</section>

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<section class="references">

## References

-   Higham, Nicholas J. 1993. "The Accuracy of Floating Point Summation." _SIAM Journal on Scientific Computing_ 14 (4): 783–99. doi:[10.1137/0914050][@higham:1993a].

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<section class="links">

[@higham:1993a]: https://doi.org/10.1137/0914050

</section>

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