Symbolic limit computation
Suppose W(t) is a function of t, and h(t,z) is a function of t and z. Define X(t,z) as follows.
var('t,z') W = function('W',t) h = function('h',t,z) X = 2*diff(h,z)(z=W)^2 / (h - h(z=W)) - 2 * diff(h,z) / (z - W)
Now, I want to compute the limit of X as z tends to W(t). I have tried the command
but this does not work. I guess a simpler example is the following.
Sage does not give the "right" answer, namely the derivative of W.
Any suggestion/comment is welcome and appreciated.