# solve a system of two equations for a derivative

I have the following defined:

sage: var('a, t');

sage: function('x, y, v, u')

sage: de1 = diff(x(t),t) - diff(y(t),t) == x(t)

sage: de2 = diff(y(t),t) == y(t)

I'd like to solve these two equations algebraically for diff(x(t),t) and diff(y(t),t).

sage: sol = solve(de1, diff(x(t),t)); works, and i get an explicit solution for diff(x(t),t), but when i try solving both equations using:

sage: sol = solve([de1, de2],diff(x(t),t),diff(y(t),t));

i get the following error:

Traceback (most recent call last): File "/projects/sage/sage-6.10/local/lib/python2.7/site-packages/smc_sagews/sage_server.py", line 905, in execute exec compile(block+'\n', '', 'single') in namespace, locals File "", line 1, in <module> File "/projects/sage/sage-6.10/local/lib/python2.7/site-packages/sage/symbolic/relation.py", line 822, in solve variables = tuple(args[0]) TypeError: 'sage.symbolic.expression.Expression' object is not iterable

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I'd appreciate any help with this. thank you.

Why not using

`desolve`

? See documentationI'm not trying to solve the differential equations just yet. i only want to solve the equations algebraically (explicitly) for the derivatives, so I can compute the Jacobian matrix of the right hand sides for further bifurcation analysis. the equations in my actual problem have parameters.

(this is pretty easy to do in Maple)

See also http://ask.sagemath.org/question/3287...