# Convolve taking too long and producing error message Integrate::idiv:

The following functions do not produce an output."f1" is a convolution of Gaussian function and my model. It took too much time and gave an error message. I have attached that error message also. How should I make it correct?

a = 3.155869951687861;
b = 0.60;
c = 0.13988193617826981;
d = 0.07;
μ = 0;
σ = 1;
f1 = Convolve[
1/(E^((x - μ)^2/(2*σ^2))*(Sqrt[2*Pi]*σ)),
a*UnitStep[x - b]*c*Sqrt[x - b]*
Divide[Pi*Divide[Sqrt[d], Sqrt[x - b]]*
Exp[Pi*Divide[Sqrt[d], Sqrt[x - b]]],
Sinh[Pi*Divide[Sqrt[d], Sqrt[x - b]]]], x, y]


Integrate::idiv: Integral of E^(0.831187/Sqrt[-0.599971 - x] - x^2/2) Csch[0.831187/Sqrt[-0.599971 - x]] UnitStep[-0.599971 - x] does not converge on {-∞, ∞}

• The limit of your second function (the one with Sinh) goes to infinity as x-> infinity, so it is no surprise that the convolution doesn't exist. – bill s Nov 2 '18 at 20:06
• Thank you very much. What would you recommend me to correct it? – Tharaka Nov 2 '18 at 20:31
• How about this: plot the two functions that you are trying to convolve. You will see that the first (the Guassian) is well behaved as x->Infinity, but that the second heads off towards infinity as x->Infinity. So maybe choose a different function (that decays to zero, for instance) in the limit. – bill s Nov 2 '18 at 21:52