Singular Manual: evaluatepfd

| #### D.15.13.3 evaluatepfd Procedure from library `pfd.lib` (see pfd_lib). Usage: evaluatepfd(dec, values[, mode]); dec list, values ideal, mode int Return: the number gotten by substituting the numbers generating the ideal `values` for the variables in the partial fraction decomposition `dec`. The list `dec` has to have the same structure as the output of pfd. `mode=1`: raise Error in case of division by 0 (default) `mode=2`: return a second integer which is 1 if the denominator becomes 0, and 0 otherwise. Example:
    LIB "pfd.lib";
    ring R = 0,(x,y),dp;
    poly f = x+2*y;
    poly g = x^2-y^2;
    // partial fraction decomposition of f/g:
    list dec = pfd(f,g);
    ==>   (-1/2) / (q2)
    ==> + (3/2) / (q1)
    ==> where
    ==> q1 = x-y
    ==> q2 = x+y
    ==> (2 terms)
    ==>
    displaypfd_long(dec);
    ==>   (-1/2)/((x+y))
    ==> + (3/2)/((x-y))
    ==> (2 terms)
    ==>
    // evaluation at x=2, y=1:
    ideal values = 2,1;
    evaluatepfd(dec,values);
    ==> 4/3
    // compare: f(2,1)/g(2,1) = (2+2*1)/(2^2-1^1) = 4/3
See also: pfd.

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