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# scipy.special.fdtr

`scipy.special.``fdtr`(x1, x2, x3[, out])
  y=fdtr(dfn,dfd,x) returns the area from zero to x under the F density function (also known as Snedcor’s density or the variance ratio density). This is the density of X = (unum/dfn)/(uden/dfd), where unum and uden are random variables having Chi square distributions with dfn and dfd degrees of freedom, respectively.

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