79 lines
2.2 KiB
Markdown
79 lines
2.2 KiB
Markdown
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<!-- Note: This file is automatically generated from source code comments. Changes made in this file will be overridden. -->
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# Function variance
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Compute the variance of a matrix or a list with values.
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In case of a (multi dimensional) array or matrix, the variance over all
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elements will be calculated.
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Additionally, it is possible to compute the variance along the rows
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or columns of a matrix by specifying the dimension as the second argument.
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Optionally, the type of normalization can be specified as the final
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parameter. The parameter `normalization` can be one of the following values:
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- 'unbiased' (default) The sum of squared errors is divided by (n - 1)
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- 'uncorrected' The sum of squared errors is divided by n
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- 'biased' The sum of squared errors is divided by (n + 1)
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Note that older browser may not like the variable name `var`. In that
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case, the function can be called as `math['var'](...)` instead of
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`math.var(...)`.
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## Syntax
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```js
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math.variance(a, b, c, ...)
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math.variance(A)
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math.variance(A, normalization)
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math.variance(A, dimension)
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math.variance(A, dimension, normalization)
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```
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### Parameters
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Parameter | Type | Description
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--------- | ---- | -----------
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`array` | Array | Matrix | A single matrix or or multiple scalar values
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`normalization` | string | Determines how to normalize the variance. Choose 'unbiased' (default), 'uncorrected', or 'biased'. Default value: 'unbiased'.
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### Returns
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Type | Description
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---- | -----------
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* | The variance
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### Throws
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Type | Description
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---- | -----------
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## Examples
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```js
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math.variance(2, 4, 6) // returns 4
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math.variance([2, 4, 6, 8]) // returns 6.666666666666667
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math.variance([2, 4, 6, 8], 'uncorrected') // returns 5
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math.variance([2, 4, 6, 8], 'biased') // returns 4
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math.variance([[1, 2, 3], [4, 5, 6]]) // returns 3.5
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math.variance([[1, 2, 3], [4, 6, 8]], 0) // returns [4.5, 8, 12.5]
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math.variance([[1, 2, 3], [4, 6, 8]], 1) // returns [1, 4]
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math.variance([[1, 2, 3], [4, 6, 8]], 1, 'biased') // returns [0.5, 2]
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```
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## See also
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[mean](mean.md),
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[median](median.md),
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[max](max.md),
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[min](min.md),
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[prod](prod.md),
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[std](std.md),
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[sum](sum.md)
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