MATLAB POLYSPACE RELEASE NOTES Manual do Utilizador descarregar pdf (Página 185)

Visualizing Data

The strength of the linear relationship betw een the two variables (how tightly

the data lies along a least-squares line through the scatter) is measured by

the covariance, computed by the MATLAB

cov function:

C12 = cov([c1 c2])

C12 =

1.0e+003 *

0.6437 0.9802

0.9802 1.7144

The results are displayed in a symmetric square matrix, with the covariance

of the i th an d j th variables in the (i, j)th position. The i th diagonal element

is the variance of the i th variable.

Covariances have the disadvantage of depending on the units used to measure

the individual variables. They are often divided by the s tandard deviations

5-15

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MATLAB POLYSPACE RELEASE NOTES Manual do Utilizador Página 185