It is clear that in general there is no decidable zero test for power series, however, we have the function truncate: (%, INT) -> % that basically creates a finite series. I hoped that it were possible to use UnivariateLaurentSeries together with this truncate function to essentially work with Laurent polynomials. I ran into a problem that I did not expect.
With the attached file I get. (9) -> zero? l0 (9) false (13) -> zero? t0 (13) false In fact, I consider this a bug. It is clearly possible to decide that l0 and t0 are 0 since their corresponding stream should be finite and at most contain zeros. Waldek, I can look into it if you also want the above return true. Ralf -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/fricas-devel/340a8f92-d7ae-f377-4e8b-066cb210ad8b%40hemmecke.org.
Z ==> Integer Q ==> Fraction Z T ==> UnivariateTaylorSeries(Q, 'x, 0) L ==> UnivariateLaurentSeries(Q, 'x, 0) lx := x :: L l := (lx^3-7*lx)/(3*lx^7-lx^4) l3 := truncate(l, 3) l0 := l3 - l3 zero? l0 reductum l0 t := taylorRep l t4 := truncate(t, 4) t0 := t4 - t4 zero? t0
