Function variance

variance<TElement>(
    source: Iterable<TElement>,
    selector?: Selector<TElement, number>,
    sample?: boolean,
): number
Calculates the variance of the numeric values produced by source.
Type Parameters
- TElement
  Type of elements within the source iterable.
Parameters
- source: Iterable<TElement>
  The source iterable to inspect.
- Optionalselector: Selector<TElement, number>
  Optional projection that extracts the numeric value for each element. Defaults to the element itself.
- Optionalsample: boolean
  When true, computes the sample variance dividing by n - 1; when false, computes the population variance dividing by n. Defaults to true.
Returns number
The calculated variance, or NaN when source is empty—or for sample variance when it contains a single element.
Throws
Re-throws any error thrown while iterating source or executing selector.

Remarks
A numerically stable single-pass algorithm (Welford's method) is used, so the iterable is enumerated exactly once regardless of size.
Example
```
const populationVariance = variance([1, 2, 3, 4, 5], x => x, false);
console.log(populationVariance); // 2
```
- Defined in src/enumerator/functions/variance.ts:19