My problem was that i needed to do implicit derivation. Something like:
sage: f=3*x^2*y^3-5*x*y+x^2-3*y^2+4*x-3*y+1 sage: f.diff(x) 9*x^2*y(x)^2*D[0](y)(x) + 6*x*y(x)^3 - 5*x*D[0](y)(x) - 6*y(x)*D[0](y) (x) + 2*x - 5*y(x) - 3*D[0](y)(x) + 4 and then substitute the value of x, y(x) (which in general will be an algebraic number) and solve for D[0](y)(x). I know that the first derivative is just minus the quotient of the partial derivatives of f, but i would need also the higher order derivatives, which forces me to repeat the previous process several times. In fact i finally found a solution the implicit derivation (see ticket 12922), but since i run into this issue of not being able to work with algebraic numbers in the symbolic ring, i thought it would be a nice feature to have. My solution is to convert these numbers into symbolic variables before feeding them to the symbolic ring, and then converting back these variables into their value when i get them back in my polynomial ring. But that sounds like a dirty hack. -- To post to this group, send an email to [email protected] To unsubscribe from this group, send an email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
