Problem with function eval

Thanks for reading my question

When I use dsolve in an ivp I get this ans:

dsolve('Dy = -yt + sin(3t) - cos(t.01) + 3sin(7*t)', 'y(0) = 0')

ans =

exp(-t^2/2)*int(exp(x2/2)(sin(3x) - cos(x/100) + 3sin(7x)), x = 0..t, IgnoreAnalyticConstraints)/exp(t2/2)

I would like to know how can I evaluate it in the interval t=0:h:20, if i just simply eval, matlab shows an error even if i ignore the analytic constraints.

Error using sym/eval (line 11)

Error: Unexpected MATLAB expression.

I think it is because eval does't work with integrals.