I know this question mayn't be new, but here is my problem: I have to solve this integral equation (numerically, of course, except from very few special cases):

$$\phi_{\nu}(t) = 1 - q\int_0^t \frac{d\psi_{\nu}}{d t'} \phi_{\nu}(t - t')\ dt'$$

Where of course I know what $\psi$ is. I can choose $q = 1$.

I tried to take a look at some past answers, but I did not find what I was looking for. The problem may be that this is a convolution integral.