Solving differential equation using matlab

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Bob Gill
Bob Gill 2023-4-2
编辑： Dyuman Joshi 2023-4-2
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)
  1 个评论
Sam Chak
Sam Chak 2023-4-2
编辑：Sam Chak 2023-4-2
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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回答（2 个）

Bjorn Gustavsson
Bjorn Gustavsson 2023-4-2
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
Dyuman Joshi
Dyuman Joshi 2023-4-2
编辑：Dyuman Joshi 2023-4-2
Ran in:
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 = 
%Adjust the interval as necessary
fplot(sol,[0 10])

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