time-to-botec/js/node_modules/@stdlib/stats/incr/sum/README.md

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@license Apache-2.0
Copyright (c) 2018 The Stdlib Authors.
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# incrsum
> Compute a sum incrementally.
<section class="intro">
The sum is defined as
<!-- <equation class="equation" label="eq:sum" align="center" raw="s = \sum_{i=0}^{n-1} x_i" alt="Equation for the sum."> -->
<div class="equation" align="center" data-raw-text="s = \sum_{i=0}^{n-1} x_i" data-equation="eq:sum">
<img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@49d8cabda84033d55d7b8069f19ee3dd8b8d1496/lib/node_modules/@stdlib/stats/incr/sum/docs/img/equation_sum.svg" alt="Equation for the sum.">
<br>
</div>
<!-- </equation> -->
</section>
<!-- /.intro -->
<section class="usage">
## Usage
```javascript
var incrsum = require( '@stdlib/stats/incr/sum' );
```
#### incrsum()
Returns an accumulator `function` which incrementally computes a sum.
```javascript
var accumulator = incrsum();
```
#### accumulator( \[x] )
If provided an input value `x`, the accumulator function returns an updated sum. If not provided an input value `x`, the accumulator function returns the current sum.
```javascript
var accumulator = incrsum();
var sum = accumulator( 2.0 );
// returns 2.0
sum = accumulator( 1.0 );
// returns 3.0
sum = accumulator( 3.0 );
// returns 6.0
sum = accumulator();
// returns 6.0
```
</section>
<!-- /.usage -->
<section class="notes">
## Notes
- Input values are **not** type checked. If provided `NaN` or a value which, when used in computations, results in `NaN`, the accumulated value is `NaN` for **all** future invocations. If non-numeric inputs are possible, you are advised to type check and handle accordingly **before** passing the value to the accumulator function.
- For long running accumulations or accumulations of large numbers, care should be taken to prevent overflow.
</section>
<!-- /.notes -->
<section class="examples">
## Examples
<!-- eslint no-undef: "error" -->
```javascript
var randu = require( '@stdlib/random/base/randu' );
var incrsum = require( '@stdlib/stats/incr/sum' );
var accumulator;
var v;
var i;
// Initialize an accumulator:
accumulator = incrsum();
// For each simulated datum, update the sum...
for ( i = 0; i < 100; i++ ) {
v = randu() * 100.0;
accumulator( v );
}
console.log( accumulator() );
```
</section>
<!-- /.examples -->
* * *
<section class="references">
## References
- Klein, Andreas. 2005. "A Generalized Kahan-Babuška-Summation-Algorithm." _Computing_ 76 (3): 27993. doi:[10.1007/s00607-005-0139-x][@klein:2005a].
</section>
<!-- /.references -->
<section class="links">
[@klein:2005a]: https://doi.org/10.1007/s00607-005-0139-x
</section>
<!-- /.links -->