Thanks DJKeenan for your additional suggestions. Many constants used in the expression "ratio" are products of numbers known to many digits and experimental values known to a few digits, so it would be difficult to specify that kind of constants to say, 16 digits, right? For example, one variable used is
where sigma is an experimental value known to 3 digits, f0 is our variable (exactly specifiable?) and 2, Pi and mu could be specified to many digits.
I will look up ScientificErrorAnalysis and Tolerances and see how they could be used. Thanks.
Thanks DJKeenan and JacquesC for your comments.
I have re-derived the long expression "ratio" in analytical form and then used evalf for numerical calculations, and found consistency between evalf and plot.
(as to whether 0.6666666666e-14 came from ((2/3)*10^(-14)), it probably did. "Ratio" came from electromagnetic wave computation in which there are constants that could originally be of rational form. In the new derivation of "ratio", I kept rational terms in rational form as long as possible before numerical evaluations.)
Thanks again for all your help!
OK thanks everyone for pointing out the reason for the inconsistent numerical answers. Sorry again for the really long expression on my post. I am not too experienced in posting on this format.
I will perform calculations using evalf as suggested.
I did try the Select Axes and then Properties. No help there.
Thanks for all your help! I did have in mind the removal of the assumption, so the suggested command
will be quite useful!