> Unless you are working with small numbers? Suppose you are dividing 1e-30 by 1e-30 than the result should still be 1 so if you return 0 when the second argume

> Unless you are working with small numbers? Suppose you are dividing 1e-30 by 1e-30 than the result should still be 1 so if you return 0 when the second argument is < 1e-6 then you're screwed. A very good point which I didn't think of! Obviously the 1e-6 figure is specific to the application. How should one avoid division by zero then? You can't figure out the relative error without a division, can you? For normal comparisons, using a relative error is the way to go but the zero case is different. On the other hand, using quantities of magnitudes in 1e-30 is already using half the exponent, a change of units may be due here.