chi2inv
Inverse of the chi-squared cumulative distribution function (iCDF).
For each element of p, compute the quantile (the inverse of the CDF) of the chi-squared distribution with df degrees of freedom. The size of x is the common size of p and df. A scalar input functions as a constant matrix of the same size as the other inputs.
Further information about the chi-squared distribution can be found at https://en.wikipedia.org/wiki/Chi-squared_distribution
See also: chi2cdf, chi2pdf, chi2rnd, chi2stat
Source Code: chi2inv
## Plot various iCDFs from the chi-squared distribution
p = 0.001:0.001:0.999;
x1 = chi2inv (p, 1);
x2 = chi2inv (p, 2);
x3 = chi2inv (p, 3);
x4 = chi2inv (p, 4);
x5 = chi2inv (p, 6);
x6 = chi2inv (p, 9);
plot (p, x1, "-b", p, x2, "-g", p, x3, "-r", ...
p, x4, "-c", p, x5, "-m", p, x6, "-y")
grid on
ylim ([0, 8])
legend ({"df = 1", "df = 2", "df = 3", ...
"df = 4", "df = 6", "df = 9"}, "location", "northwest")
title ("Chi-squared iCDF")
xlabel ("probability")
ylabel ("values in x")
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