1. The problem statement, all variables and given/known data I need to calculate the integral of (1/(at+b))e^(-t^2), that is, a negative quadratic exponential divided by a linear function at+b. I need to integrate between some positive x and +infinity. 2. Relevant equations 3. The attempt at a solution I could find the integral for b=0. In fact the integral of 1/(at) e^(-t^2) between x>0 and +infinity is equal to -1/(2a) Ei(-x^2) where Ei(x) is the exponential integral function defined as -Ei(-x)=E1(x)=Integral of (1/t)e^-t between x and +infinity. Since Ei can be expressed through the Incomplete Gamma function and I have the latter in Excel, in this case my problem would be - at least computationally - solved. However, when b is not zero I cannot find any solution. Any help guys?