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D.15.12.3 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
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See also:
pfd.
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