When 'integrate' returns a list of results, there are conditions associated with them. More specifically, it tries to ensure (y)^(1/n) is real when n is even, aka ensure y is positive.
So in the example of 'integrate(1/(x^4+2*a*x^2+a^2-1),x)', the first answer, (-a-1) and (-a+1) should be positive, aka a <=-1 The second, (-a-1) and (a-1) should be positive, which is impossible. (Current code checks sign of the product.) The third (a+1) and (-a+1) should be positive, aka -1<=a<=1 The fourth (a-1) and (a+1) should be positive, aka a>=1. Clearly there are much room for improvement in the algorithm. See 'irexpand.spad', especially the function 'pairsum' and 'compatible?'. -- 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.
