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chdtrc
Complemented Chi-square distribution.SYNOPSIS:
double v, x, y, chdtrc();
y = chdtrc(v, x);
DESCRIPTION:
Returns the area under the right hand tail (from x to infinity) of the Chi square probability density function with v degrees of freedom:
inf.
-
1 | | v/2-1 -t/2
P(x | v) = ----------- | t e dt
v/2 - | |
2 | (v/2) -
x
where x is the Chi-square variable.
The incomplete gamma integral is used, according to the formula:
y = chdtr(v, x) = igamc(v/2.0, x/2.0).
The arguments must both be positive.
ACCURACY:
See the igamc() Help topic.
ERROR MESSAGES:
message condition value returned
domain x < 0 or v < 1 0.0