I have no general solution. But maybe you look at Chapter 0.8 here http://fricas.github.io/book.pdf
You can create your own rules that do the things of the sinCosExpandRules somewhat backwards if you just exchange the things on the left/right of the == sign. However, this does not work in general, since (as far as I know) the rule will not apply of the expression (that you apply the rules to) is disturbed a bit so that no match is found. Ralf On 01/24/2017 11:38 PM, Constantine Frangos wrote: > I wanted to ask for some assistance in using fricas to > perform some specific trigonometric simplifications. > > (1) The relevant fricas commands or re-write rules to perform > the following simplifications. > > t1 = cos(x)*sin(y)-sin(x)*cos(y) to sin(y-x), > > t2 = cos(x)*cos(y)-sin(x)*sin(y) to cos(x+y). > > (2) I have expressions which are sums of products of the > above-mentioned terms. For example, > > expr = t1*cos(x3) + 5 + tan(q)*tan(w) + t2*w*cos(a) > + t1*t2*r3 > > How can fricas commands be applied in order to simplify > expr to > > expr_s = sin(y-x)*cos(x3) + 5 + tan(q)*tan(w) + > cos(x+y)*w*cos(a) + sin(y-x)*cos(x+y)*r3 ? > > > Thanks very much. > > Regards, > Constantine Frangos. > -- 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 fricas-devel+unsubscr...@googlegroups.com. To post to this group, send email to fricas-devel@googlegroups.com. Visit this group at https://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/d/optout.
