123 lines
4.2 KiB
Plaintext
123 lines
4.2 KiB
Plaintext
|
|
{{alias}}( N, correction, x, stride )
|
|
Computes the variance of a single-precision floating-point strided array
|
|
ignoring `NaN` values and using a one-pass algorithm proposed by Youngs and
|
|
Cramer.
|
|
|
|
The `N` and `stride` parameters determine which elements in `x` are accessed
|
|
at runtime.
|
|
|
|
Indexing is relative to the first index. To introduce an offset, use a typed
|
|
array view.
|
|
|
|
If `N <= 0`, the function returns `NaN`.
|
|
|
|
If every indexed element is `NaN`, the function returns `NaN`.
|
|
|
|
Parameters
|
|
----------
|
|
N: integer
|
|
Number of indexed elements.
|
|
|
|
correction: number
|
|
Degrees of freedom adjustment. Setting this parameter to a value other
|
|
than `0` has the effect of adjusting the divisor during the calculation
|
|
of the variance according to `n - c` where `c` corresponds to the
|
|
provided degrees of freedom adjustment and `n` corresponds to the number
|
|
of non-`NaN` indexed elements. When computing the variance of a
|
|
population, setting this parameter to `0` is the standard choice (i.e.,
|
|
the provided array contains data constituting an entire population).
|
|
When computing the unbiased sample variance, setting this parameter to
|
|
`1` is the standard choice (i.e., the provided array contains data
|
|
sampled from a larger population; this is commonly referred to as
|
|
Bessel's correction).
|
|
|
|
x: Float32Array
|
|
Input array.
|
|
|
|
stride: integer
|
|
Index increment.
|
|
|
|
Returns
|
|
-------
|
|
out: number
|
|
The variance.
|
|
|
|
Examples
|
|
--------
|
|
// Standard Usage:
|
|
> var x = new {{alias:@stdlib/array/float32}}( [ 1.0, -2.0, NaN, 2.0 ] );
|
|
> {{alias}}( x.length, 1, x, 1 )
|
|
~4.3333
|
|
|
|
// Using `N` and `stride` parameters:
|
|
> x = new {{alias:@stdlib/array/float32}}( [ -2.0, 1.0, 1.0, -5.0, 2.0, -1.0 ] );
|
|
> var N = {{alias:@stdlib/math/base/special/floor}}( x.length / 2 );
|
|
> {{alias}}( N, 1, x, 2 )
|
|
~4.3333
|
|
|
|
// Using view offsets:
|
|
> var x0 = new {{alias:@stdlib/array/float32}}( [ 1.0, -2.0, 3.0, 2.0, 5.0, -1.0 ] );
|
|
> var x1 = new {{alias:@stdlib/array/float32}}( x0.buffer, x0.BYTES_PER_ELEMENT*1 );
|
|
> N = {{alias:@stdlib/math/base/special/floor}}( x0.length / 2 );
|
|
> {{alias}}( N, 1, x1, 2 )
|
|
~4.3333
|
|
|
|
{{alias}}.ndarray( N, correction, x, stride, offset )
|
|
Computes the variance of a single-precision floating-point strided array
|
|
ignoring `NaN` values and using a one-pass algorithm proposed by Youngs and
|
|
Cramer and alternative indexing semantics.
|
|
|
|
While typed array views mandate a view offset based on the underlying
|
|
buffer, the `offset` parameter supports indexing semantics based on a
|
|
starting index.
|
|
|
|
Parameters
|
|
----------
|
|
N: integer
|
|
Number of indexed elements.
|
|
|
|
correction: number
|
|
Degrees of freedom adjustment. Setting this parameter to a value other
|
|
than `0` has the effect of adjusting the divisor during the calculation
|
|
of the variance according to `n - c` where `c` corresponds to the
|
|
provided degrees of freedom adjustment and `n` corresponds to the number
|
|
of non-`NaN` indexed elements. When computing the variance of a
|
|
population, setting this parameter to `0` is the standard choice (i.e.,
|
|
the provided array contains data constituting an entire population).
|
|
When computing the unbiased sample variance, setting this parameter to
|
|
`1` is the standard choice (i.e., the provided array contains data
|
|
sampled from a larger population; this is commonly referred to as
|
|
Bessel's correction).
|
|
|
|
x: Float32Array
|
|
Input array.
|
|
|
|
stride: integer
|
|
Index increment.
|
|
|
|
offset: integer
|
|
Starting index.
|
|
|
|
Returns
|
|
-------
|
|
out: number
|
|
The variance.
|
|
|
|
Examples
|
|
--------
|
|
// Standard Usage:
|
|
> var x = new {{alias:@stdlib/array/float32}}( [ 1.0, -2.0, NaN, 2.0 ] );
|
|
> {{alias}}.ndarray( x.length, 1, x, 1, 0 )
|
|
~4.3333
|
|
|
|
// Using offset parameter:
|
|
> var x = new {{alias:@stdlib/array/float32}}( [ 1.0, -2.0, 3.0, 2.0, 5.0, -1.0 ] );
|
|
> var N = {{alias:@stdlib/math/base/special/floor}}( x.length / 2 );
|
|
> {{alias}}.ndarray( N, 1, x, 2, 1 )
|
|
~4.3333
|
|
|
|
See Also
|
|
--------
|
|
|