Problems with matlab symbolic dsolve function

1 次查看(过去 30 天)
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?

回答(2 个)

Amit Kumar
Amit Kumar 2014-10-16
Any ideas?

Stefan Wehmeier
Stefan Wehmeier 2014-10-30
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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