The Variance component calculates the empirical variance of its input signal.

The parameter $t_{\mathrm{\epsilon }}$ is used to guard against division by zero (the variance computation starts at $t_0\+t_{\mathrm{\epsilon }}$ and before that time instant $y\=0$).

The variance of a signal is also equal to its mean power.

$y\=\{\begin{array}{cc}\max \left(0\,\mathrm{var}\right)& t_0\+t_{\mathrm{\epsilon }}\le t\\ 0& \mathrm{otherwise}\end{array}$

$\frac{d\mathrm{\mu }}{\mathrm{dt}}\=\{\begin{array}{cc}\frac{u-\mathrm{\mu }}{t-t_0}& t_0\+t_{\mathrm{\epsilon }}\le t\\ 0& \mathrm{otherwise}\end{array}$

$\frac{d\mathrm{var}}{\mathrm{dt}}\=\{\begin{array}{cc}\frac{{\left(u-\mathrm{\mu }\right)}^2-\mathrm{var}}{t-t_0}& t_0\+t_{\mathrm{\epsilon }}\le t\\ 0& \mathrm{otherwise}\end{array}$

The component described in this topic is from the Modelica Standard Library. To view the original documentation, which includes author and copyright information, click here.