On Saturday, April 7, 2012 1:49:22 PM UTC-4, Duc Trung Ha wrote: > > Hola, > > I was wondering about following eerie behavior of "solve" function: > > On the one hand, "force" value of "to_poly_solve" option seems to be more > powerful as for periodicity of solutions: > > sage: solve(tan(x)==1,x,to_poly_solve=True) > [x == 1/4*pi] > sage: solve(tan(x)==1,x,to_poly_solve="force") > [x == 1/4*pi + pi*z275] > > On the other hand, "True" value of "to_poly_solve" occasionally gives out > better outputs: > > sage: solve(sin(x)/cos(x)-1,x,to_poly_solve=True) > [x == 1/4*pi + pi*z299] > sage: solve(sin(x)/cos(x)-1,x,to_poly_solve="force") > [] > > However, "tan(x)==1" appears to me as an equivalent form of > "sin(x)/cos(x)-1==0". >
That's interesting. I think that from our viewpoint, since we rely pretty heavily on Maxima's `to_poly_solve` package at that point, the "right" answer would be to 1) find Maxima commands that would do the same thing (you'll have to look a tiny bit at the source code for solve, available at http://hg.sagemath.org/sage-main/file/c239be1054e0/sage/symbolic/expression.pyx#l7560 and further) 2) test them in the latest (5.27) Maxima 3) then pass it on to the Maxima list and in particular Barton Willis, the author of this package, who would certainly be interested in anything that would improve it. My guess is that in the first case, to_poly_solve has a way of converting tan to something clever that then gets solved, but in the second case doesn't and so returns the empty set of solutions ('force' makes to_poly_solve the only way we try to solve an equation). If you could do this, I'm sure they would find it quite useful! Thanks. -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
