Hello Aaron, Thanks for pointing out this thread (I did search the group but missed it): http://groups.google.com/group/sympy/browse_thread/thread/7a4ab2af17b3c10d/90ba1a6bebb59eb9
I am talking about a similar idea but I am looking also for calculus operations like differentiation. Thanks, Amit On Jun 30, 9:37 am, Aaron Meurer <[email protected]> wrote: > I think he wants to do things with symbolic matrices, like what > Matthew proposed in another thread. Differentiating matrices > symbolically is indeed tricky because you have to be careful about > commutativity. > > Aaron Meurer > > > > > > > > On Thu, Jun 30, 2011 at 12:21 AM, SherjilOzair <[email protected]> wrote: > > Hello Amit, > > The line of code you have given is not clear. Could you give a more > > concrete example of a functionality that you're expecting ? > > > If you want to calculate the hessian of a function, Sympy has a > > hessian function which takes in a function and a list of variables of > > the function, and returns the hessian matrix of size m * m, where m is > > number of variables. > > > In [4]: f = x**2*y > > > In [5]: f > > Out[5]: > > 2 > > x ⋅y > > > In [6]: syms = [x,y] > > > In [7]: hessian(f, syms) > > Out[7]: > > ⎡2⋅y 2⋅x⎤ > > ⎢ ⎥ > > ⎣2⋅x 0 ⎦ > > > As to about other matrix calculus functions, it would help if you > > could show what exactly do you want along with the corresponding > > output you expect. > > > -Sherjil Ozair > > > On Jun 30, 7:10 am, Amit <[email protected]> wrote: > >> Hi, > > >> I am studying machine learning and lately I had to do some matrix > >> calculus. I am using the 'The Matrix cookbook' to calculate things > >> like the gradient and hessian of expressions like: > > >> {Z \alpha}^T (Z^T diag(\alpha) Z - ...)^{-1} Z \alpha > > >> where Z is a matrix and alpha a vector. This can get pretty ugly and > >> tedious when done by hand. > >> I looked for some automatic way to do this i.e. a CAS, but didn't find > >> any (I am looking for something that can do this symbolically and not > >> numerically). > >> I was wandering why is it so. Is it too complicated? or maybe its not > >> well defined? > > >> Thanks, > >> Amit > > > -- > > You received this message because you are subscribed to the Google Groups > > "sympy" group. > > 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 > > athttp://groups.google.com/group/sympy?hl=en. -- You received this message because you are subscribed to the Google Groups "sympy" group. 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/sympy?hl=en.
