The code attached produces an error due to missing multiplication operators. You may replace the line 10 of your code where the 'response' variable is calculated with the below line:
response = 1/(m*wd)*int(F*exp(-z*wn*(ta-tau))*sin(wd*(ta-tau)),tau,0,ta);
You may also check out the vpa function that substitutes the value of 3.5 to the ‘response’ symbolic expression. You may use the following line of code:
Hope this helps!