Quote:
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Originally Posted by sanddrag
For everyone: Did you know excel can plot on a logrithmic scale? Also, did you know you can do a best fit line? I never knew these things before so that's why I'm telling.
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I've got an added challenge: get Excel to print out a graph in (what I think is) y —> log(log(y)) format. I've got set of data for kinematic viscosity vs. temperature for 5W-30 and Mercon SP oils, which I wanted to put in Excel—but Excel seems only capable of doing conventional log(y) graphs, and I haven't bothered to check if Mathcad (which I don't really like) can handle it.
Since this description likely makes no sense to someone who's never seen this graph before, I'll try to clarify: instead of having the major divisions of 10
i, for all integers
i, each displayed at a fixed distance apart on the y-axis (such as would be the case with log(y) graph paper), this graph displays them at ever-decreasing distances apart, in the same proportions as the logarithmic spacing (so a big segment for 10
1, and decreasing segments for 10
2, 10
3, 10
4,...).
Why all the thought about how to do this? Well, theoretically, kinematic viscosity should appear mostly linear on this y —> log(log(y)) plot, rather than logarithmic or worse. I wanted to see how well a list of measured data points in a chart compared to the (dubiously accurate) graph which I already had.