I have five, very precise, experimental values of refractive index for five different wavelengths and would like to draw the Sellmeier fit of the form:
n^2=A1+A2/(1-A3/lambda^2) + A4/(1-A5/lambda^2)
So, to find A1, A2, A3, A4 and A5 parameters I need to solve the system of five equations...