I have this graph attached below. I want to be able to just specify e/D and have mathcad spit out K. What is the easiest way to do this? Maybe some sort of lookup table? I'm not sure.
I think I understand. So column 0 would be e/D and column 1 would be K. I would use:
linterp(vx, vy, x)
where vx is column 0 and vy is column 1 and x is my e/D value?
Assuming that you can't find an analytical curve fit in the literature,
You can create a general function, written as a program to interpolate D/w, Ftu/Eeu, Fty/Fut
Digitize each curve with as much accuracy as you want, as suggested above, for every curve.
Then with a program, interpolate along a curve for a given Ftu/Eeu.
If you fall between curves, then further interpolate between two curves.
If you fall between graphs, then further interpolate between graphs.
The program is pretty easy, digitzing the curves is a pain.
This looks a superb feature but it doesn't seem to yield the correct results. Can you confirm that you are matching the graph values?
Typing phi(X)= & phi(Y)= next to, or after the final graph should present your data. Table "R" is the original slected data without the "known values" (control click & shift click) to maintain the profile.
I do not use it, just have it in my tool box.
I have converted some tables/plots into Mathcad WebSheets for Dow Chemical.
See the article:
The Mathcad WebSheets - http://twt.mpei.ac.ru/MCS/Worksheets/Hydro/La-De-Re.xmcd
with this origin plot:
You might be able to use "cubic spline interpolation" to create surfaces.
Look it up in the "Help" files. There is a quicksheet there on "2D Interpolation" that should be useful.
This will take a bit of work, but it might be worthwhile if you use the graphs all the time.
I have discussed the Digitize function passed by Valery many times before, but as Norm indicated it requires a clean graph, which can be achieved using paint.