# Solving differential equation using matlab

6 vues (au cours des 30 derniers jours)
Bob Gill le 2 Avr 2023
Hey everyone.
I just need some help solving this differential equation with matlab, and then plotting it.
This is my current code, but it does not seem to work.
y = dsolve('D2x-2Dx+5x=dirac(t-5)', 'x(0)=0, Dx(0)=0, t=0', 't')
ezplot(y)
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Sam Chak le 2 Avr 2023
Modifié(e) : Sam Chak le 2 Avr 2023
Bob, it is invalid to name variables that begin with digits, like "2Dx" and "5x". For details, see:
https://www.mathworks.com/help/matlab/matlab_prog/variable-names.html
Instead of pasting the full solution where you can directly copy, it will be more meaningful to find out which example in dsolve that you refer.
Knowing that will help improving the way of technical writing in dsolve documentation that beginners can search for relevant examples, follow the mechanics and understand the code easily.

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### Réponses (2)

Bjorn Gustavsson le 2 Avr 2023
Do step-by-step and avoid using strings, like this:
syms t real
syms x(t)
Dx = diff(x);
D2x = diff(x,2);
y = dsolve(D2x - 2*Dx + 5*x == dirac(t-5),x(0)==0, Dx(0)==0);
ezplot(y)
HTH
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Dyuman Joshi le 2 Avr 2023
Modifié(e) : Dyuman Joshi le 2 Avr 2023
Hello Bob,
It is recommended to use symbolic variables instead of using string or char arrays in dsolve (as you can see in the documentation) and it is recommended to use fplot over ezplot
%single variable function
syms x(t)
Dx = diff(x);
%differential eequation6
eq = diff(x,2) - 2*diff(x) + 5*x == dirac(t-5)
eq(t) =
%Initial conditions
con = [x(0) == 0; Dx(0) == 0];
sol = dsolve(eq,con)
sol =
fplot(sol,[0 10])
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