Compute a corrected sample standard deviation incrementally.
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> Compute a [corrected sample standard deviation][sample-stdev] incrementally.
The [corrected sample standard deviation][sample-stdev] is defined as
``bash`
npm install @stdlib/stats-incr-stdev
`javascript`
var incrstdev = require( '@stdlib/stats-incr-stdev' );
#### incrstdev( \[mean] )
Returns an accumulator function which incrementally computes a [corrected sample standard deviation][sample-stdev].
`javascript`
var accumulator = incrstdev();
If the mean is already known, provide a mean argument.
`javascript`
var accumulator = incrstdev( 3.0 );
#### accumulator( \[x] )
If provided an input value x, the accumulator function returns an updated [corrected sample standard deviation][sample-stdev]. If not provided an input value x, the accumulator function returns the current [corrected sample standard deviation][sample-stdev].
`javascript
var accumulator = incrstdev();
var s = accumulator( 2.0 );
// returns 0.0
s = accumulator( 1.0 ); // => sqrt(((2-1.5)^2+(1-1.5)^2) / (2-1))
// returns ~0.7071
s = accumulator( 3.0 ); // => sqrt(((2-2)^2+(1-2)^2+(3-2)^2) / (3-1))
// returns 1.0
s = accumulator();
// returns 1.0
`
- 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.
`javascript
var randu = require( '@stdlib/random-base-randu' );
var incrstdev = require( '@stdlib/stats-incr-stdev' );
var accumulator;
var v;
var i;
// Initialize an accumulator:
accumulator = incrstdev();
// For each simulated datum, update the sample standard deviation...
for ( i = 0; i < 100; i++ ) {
v = randu() * 100.0;
accumulator( v );
}
console.log( accumulator() );
`
*
- [@stdlib/stats-incr/kurtosis][@stdlib/stats/incr/kurtosis]: compute a corrected sample excess kurtosis incrementally.
- [@stdlib/stats-incr/mean][@stdlib/stats/incr/mean]: compute an arithmetic mean incrementally.
- [@stdlib/stats-incr/mstdev][@stdlib/stats/incr/mstdev]: compute a moving corrected sample standard deviation incrementally.
- [@stdlib/stats-incr/skewness][@stdlib/stats/incr/skewness]: compute a corrected sample skewness incrementally.
- [@stdlib/stats-incr/summary][@stdlib/stats/incr/summary]: compute a statistical summary incrementally.
- [@stdlib/stats-incr/variance][@stdlib/stats/incr/variance]: compute an unbiased sample variance incrementally.
*
This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].
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---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules
[deno-url]: https://github.com/stdlib-js/stats-incr-stdev/tree/deno
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[umd-url]: https://github.com/stdlib-js/stats-incr-stdev/tree/umd
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[esm-url]: https://github.com/stdlib-js/stats-incr-stdev/tree/esm
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[sample-stdev]: https://en.wikipedia.org/wiki/Standard_deviation
[@stdlib/stats/incr/kurtosis]: https://www.npmjs.com/package/@stdlib/stats-incr-kurtosis
[@stdlib/stats/incr/mean]: https://www.npmjs.com/package/@stdlib/stats-incr-mean
[@stdlib/stats/incr/mstdev]: https://www.npmjs.com/package/@stdlib/stats-incr-mstdev
[@stdlib/stats/incr/skewness]: https://www.npmjs.com/package/@stdlib/stats-incr-skewness
[@stdlib/stats/incr/summary]: https://www.npmjs.com/package/@stdlib/stats-incr-summary
[@stdlib/stats/incr/variance]: https://www.npmjs.com/package/@stdlib/stats-incr-variance