On analytical versus numerical integration in tristimulus calculations

If one assumes that the CIE recommendations for linear interpolation of illuminant and observer data between unit nanometers define these data as analytical functions, and accepts similar linear interpolation of the spectral radiance factor, an analytical equation can be derived for calculating tristimulus values. This article shows that, even in extreme cases, use of this more complex equation gives results that are not significantly different from those obtained by simple summation.