Hello all

I am new to Mathematica and have some trouble doing my work done.

In a paper, I encountered the following system of differential equations:

y'(t) = - 1/0.401 y(t) + u(t) / 0.401
z'(t) = -447 exp(2.24 z(t)) z(t) + y(t) 

Now I would like to have that system solved, for y(0) =0, z(0) = 0. I addition I fixed u(t) to 20 (can I leave it as a variable?).

I ask Mathematica to solve the system as follows:

eqns = {y'[t] == -447.0 Exp[2.24 y[t]] y[t] + z[t], z'[t] == (-z[t] + 20)/0.401 , y[0] == 0, z[0] == 0} sol = NDSolve[eqns, {y, z}, {t, 0., 100.}]

Mathematica returns

{{y->InterpolatingFunction[Domain: {{0.,100.}}
Output: scalar

],z->InterpolatingFunction[Domain: {{0.,100.}}
Output: scalar

]}}

Now my question is, what can I do with this output? Can I ask Mathematica to return a function that somehow describes the output?

Thank you,

Niki