chdtri

Inverse of complemented Chi-square distribution.

SYNOPSIS:

double df, x, y, chdtri();
x = chdtri(df, y);

DESCRIPTION:

Finds the Chi-square argument x, such that the integral from x to infinity of the Chi-square density is equal to the given cumulative probability y.

This is accomplished using the inverse gamma integral function and the relation:

x/2 = igami(df/2, y);

ACCURACY:

See igami

ERROR MESSAGES:

message condition value returned
domain y < 0 or y > 1 0.0
v < 1