# Measures of Spread (Standard Deviation and Variance) (G Dataflow)

Version:

Computes the mean, standard deviation, and variance of the values in a sequence.

## reset

A Boolean that specifies whether to reset the internal state of the node.

 True Resets the internal state of the node. False Does not reset the internal state of the node.

This input is available only if you wire a double-precision, floating-point number to x.

Default: False

## x

The input sequence.

This input accepts a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

## weighting

Weighting mode that this node uses to compute the input sequence.

Name Description
Sample

Calculates the sample standard deviation and variance.

Population

Calculates the population standard deviation and variance.

Default: Sample

## sample length

Length of each set of data.

The node performs computation for each set of data. sample length must be greater than zero.

This input is available only if you wire a double-precision floating-point number to x.

Default: 100

## error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

## mean

Mean, or average, of the values in the input sequence.

## standard deviation

Standard deviation calculated from the values in the input sequence.

## variance

Calculated variance of the values in the input sequence.

## error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

## Algorithm for Computing the Mean, Deviation, and Variance

The node calculates the output values using the following equations.

$\mu =\frac{1}{n}\underset{i=0}{\overset{n-1}{\sum }}{x}_{i}$

where $\mu$ is mean and n is the number of elements in x.

${\sigma }^{2}=\frac{1}{n}\underset{i=0}{\overset{n-1}{\sum }}{\left({x}_{i}-\mu \right)}^{2}$

where

• $\sigma$is standard deviation
• ${\sigma }^{2}$is variance
• $\mu$is mean
• w is n when weighting is Population and (n - 1) when weighting is Sample

Where This Node Can Run:

Desktop OS: Windows

FPGA: This product does not support FPGA devices