Problems with matlab symbolic dsolve function

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Amit Kumar
Amit Kumar on 16 Oct 2014
Answered: Stefan Wehmeier on 30 Oct 2014
Hi I feel that something is going wrong with matlab dsolve function. Here is simple code:
syms y x
dsolve('9*D2y+y=x*exp(-x^2)')
answer:
x*exp(-x^2) + C2*cos(t/3) + C3*sin(t/3)
Solution does not have the first term. Still, how matlab gives such answer? Any ideas?

Answers (2)

Amit Kumar
Amit Kumar on 16 Oct 2014
Any ideas?

Stefan Wehmeier
Stefan Wehmeier on 30 Oct 2014
The correct syntax is
syms y(x)
dsolve(diff(y, x, x) +y==x*exp(-x^2))
as it declares y as a function of x (and not of t). Alternatively, you can add x as a second argument to your input; but we do not recommend to use character strings.

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