The reason why you see 0e+0 is most likely that the number of leading zeros after the decimal is higher than what you asked to display. Then JMP or any other software can only represent what is given by the calculations which is 0 then.
However, you should be aware of floating point arithmetic and what it is capable of calculating.1e-17 usually is the point where a floating point number cannot differentiate from 0, which means every non-zero value smaller than 1e-17 will be interpreted in calcualtions as zeros. That's (within others) for what symbolic math is good for, because you use symbolic values to deal with that, and the maths behind will calculate further on with mathematical rules rather than actual numeric calculations. Just a side note
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