I have two spectra that I'd like to compare. One is the observed spectrum of HD 93521, an O-type star commonly used as a spectrophotometric standard. The other is the known, instrinsic spectrum of this star. By dividing the observed spectrum by the intrinsic one, I will be able to deduce the combined atmospheric and instrumental response of the system on the night that the observing was done. The problem I am having is more of a comp sci problem. The wavelength arrays for the two spectra have totally different spacings (bin sizes). The observational data varies from about 3111 - 5613 angstroms with 4175 data points, evenly spaced. For the instrinsic spectrum, the wavelengths are NOT evenly spaced (because this is an amalgamation of multiple data sets for this star), and there are only 1919 data points in the wavelength range of interest. What would be the best way of going about modifying the intrinsic spectrum so that it might be compared to the observed one? I could just interpolate, but then I am worried that I am basically just adding made up data points to the spectrum, and that I might destroy some features of the spectrum (and add some spurious other ones).