I have a merit function 1 non-zero value, 8.6462E-004 and a weight of 1. Assume the figure of merit value is given by:

In this case FMT should equal 8.6462E-004 and it does. Now change the weight on another operand to 1 but the operand has zero value. Now FMT = 0.000611, which still obeys the formula above. Change another weight to 1 on a zero operand. Now there are 3 weights (all 1) and 1 non-zero operand (above). The formula yields: FMT = 8.6462E-004/SQRT (1+1+1) = 0.000499…which is still correct. Now change the weight set to (1,2,1) we should get: 8.6462E-004/SQRT(1+2^2+1)=0.000353 but instead get 0.00432.

The formula above does not appear to be correct, so what is the correct formula?