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A frequency curve connects all values of the quantity for j = 1, n with the common property of equal probability of non-exceedance. Generally a group of curves is considered which represents specific points of the cumulative frequency distribution for each j. Let the frequency curves be represented by matrix B~B(k,j)~ , (k = 1, nf; j = 1, n) where nf is the number of frequencies for which curves are created, then values for Bk,j0 are obtained by linear interpolation:
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