I get the following error message when I include the conditional into my definition for function f[a_}: Invalid integration variable or limit(s). Without this conditonal statement,
x equals a negative number, which is not realistic. The smallest number x[t] can equal is 0. I believe the error message is because
x[t] takes on a constant numerical value due to the conditional statement and it forms the
d(x[t]) part of the integral. Do you have any suggestions to get around this? If x[t]<=0.0001, I would like x'[t]=0 and y'[t]=-2*a*y[t].
Here are my equations: