> Yes. But my impression (maybe wrong) was that algebraic > calculation can be done without looking at signs.
In this case, to determine the number of roots of UP(x, POLY INT), we have to compute SturmHabichtSequence first, during this process, we need the sign of leading coefficient sc1, it is used afterwards like "sc1^(p-r-1)". The example from the reference is this: Q : UP(x, POLY INT) := x^8 - 2*x^6 + t*x^5 - x^2 - x + 1 SturmHabichtCoefficients(Q,1) -- gives same result in the reference Top five coefficients are: 1, 8, 32, - 72t^2 + 192, - 135t^4 - 272t^2 + 1152, ...... To computer the number of roots, we need to know the sign of these coefficients, we have to evaluate t at some number to do so. This usage of sign is pretty simple: typically the input will have a integer leadingcoefficient instead of (t^2+1), and I use ToolsForSign simply to avoid writing if R has RetractableTo Fraction Integer then retractIfCan(r)@Union(Fraction Integer, "failed") if R has RetractableTo Integer then retractIfCan(r)@Union(Integer, "failed") again. -- 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 post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/d/optout.
