roah's profile - activity

Try this:

sage: solutions=solve(list(f.diff()),[x,y],solution_dict=True)
sage: solutions
[{y: 0, x: -I}, {y: 0, x: I}, {y: -1/2, x: 0}]
sage: H.subs(solutions[2])
[(x, y) |--> -1  (x, y) |--> 0]
[ (x, y) |--> 0  (x, y) |--> 2]

Or this:

sage: H(x,y).subs(solutions[2])
[-1  0]
[ 0  2]

I'm not sure exactly what output you are looking for.

The documentation for solve has some more information about this keyword.

Thanks, kcrisman! Maybe it is possible to include these lines into Sage Reference Manual? In the manual one enters the point manually... I don't know how to do this...

Thanks, niles!

Let's consider a modified example from Sage reference manual

f(x,y)=x^2*y+y^2+y
solutions=solve(list(f.diff()),[x,y])
the_solution=solutions[2]
H=f.diff(2);  # Hessian matrix

How can i properly substitute the_solution into H?

I have tried:

H(x,y).subs(the_solution) - does not work.

This will work for H(x,y).subs(x==0)

H(x,y).subs_expr(*the_solution) - does not work.

This will work for f(x,y).subs_expr(*the_solution)

Thanks! Will try...

You can try to apply the patch attached to ticket #6344.

The patch review walk through contains instructions on how to apply patches.

When i try:

f(x) = function('f',x)
g = diff(f(x),x)
latex(g)

i get:

D[0]\left(f\right)\left(x\right)

but i would like to get something like:

g'\left(x\right)

How can i do this with Sage?