User`s guide

Standard Deviation

5-419

Running Operation

When the Running standard deviation check box is selected, the block tracks

the standard deviation of each channel in a time-sequence of M-by-N inputs.

For sample-based inputs, the output is a sample-based M-by-N matrix with

each element y

containing the standard deviation of element u

over all inputs

since the last reset. For frame-based inputs, the output is a frame-based

M-by-N matrix with each element y

containing the standard deviation of the

jth column over all inputs since the last reset, up to and including element u

of the current input.

If the

Reset port parameter is set to Non-zero sample, the optional Rst port

is enabled and the block resets the running standard deviation when the scalar

input at the

Rst port is nonzero. (The Rst port can be disabled by setting the

Reset port parameter to None.)

As in basic operation, length-M 1-D vector inputs and sample-based length-M

row vector inputs are both treated as M-by-1 column vectors.

Example The Standard Deviation block in the model below calculates the running

standard deviation of a frame-based 3-by-2 (two-channel) matrix input,

u. The

running standard deviation is reset at t=2 by an impulse to the block’s

Rst port.

The Standard Deviation block has the following settings:

•

Running standard deviation =

•

Reset port = Non-zero sample

The Signal From Workspace block has the following settings:

•

Signal = u

•Sample time = 1/3

•Samples per frame = 3