The
CHISQR_PDF
function computes the probability *
P*
that, in a
Chi-square distribution with *
Df*
degrees of freedom, a random variable *
X*
is less than or equal to a user-specified cutoff value *
V*
.

This routine is written in the IDL language. Its source code can be found in the file ```
chisqr_pdf.pro
```

in the ```
lib
```

subdirectory of the IDL distribution.

Use the following command to compute the probability that a random variable X, from the Chi-square distribution with three degrees of freedom, is less than or equal to 6.25. The result should be 0.899939.

Compute the probability that a random variable X from the Chi-square distribution with three degrees of freedom, is greater than 6.25. The result should be 0.100061.

BINOMIAL , CHISQR_CVF , F_PDF , GAUSS_PDF , T_PDF