Say I want to average these two functions; they have out-of-range for values undefined....
Have you tried using If() to set them to zero instead of undefined?
If(R(x, y) ≠ R(x, y), 0, R(x, y))
If(S(x, y) ≠ S(x, y), 0, S(x, y))
if makes the system very slow...
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