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# incrmidrange

> Compute a [mid-range][mid-range] incrementally.

<section class="intro">

The [**mid-range**][mid-range], or **mid-extreme**, is the arithmetic mean of maximum and minimum values. Accordingly, the [mid-range][mid-range] is the midpoint of the [range][range] and a measure of central tendency.

</section>

<!-- /.intro -->

<section class="usage">

## Usage

```javascript
var incrmidrange = require( '@stdlib/stats/incr/midrange' );
```

#### incrmidrange()

Returns an accumulator `function` which incrementally computes a [mid-range][mid-range].

```javascript
var accumulator = incrmidrange();
```

#### accumulator( \[x] )

If provided an input value `x`, the accumulator function returns an updated [mid-range][mid-range]. If not provided an input value `x`, the accumulator function returns the current [mid-range][mid-range].

```javascript
var accumulator = incrmidrange();

var midrange = accumulator();
// returns null

midrange = accumulator( -2.0 );
// returns -2.0

midrange = accumulator( 1.0 );
// returns -0.5

midrange = accumulator( 3.0 );
// returns 0.5

midrange = accumulator();
// returns 0.5
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   Input values are **not** type checked. If provided `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.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var randu = require( '@stdlib/random/base/randu' );
var incrmidrange = require( '@stdlib/stats/incr/midrange' );

var accumulator;
var v;
var i;

// Initialize an accumulator:
accumulator = incrmidrange();

// For each simulated datum, update the mid-range...
for ( i = 0; i < 100; i++ ) {
    v = randu() * 100.0;
    accumulator( v );
}
console.log( accumulator() );
```

</section>

<!-- /.examples -->

<section class="links">

[range]: https://en.wikipedia.org/wiki/Range_%28statistics%29

[mid-range]: https://en.wikipedia.org/wiki/Mid-range

</section>

<!-- /.links -->