I’d like to understand how a interferogram might be constructed in Excel. Read my plan below; but I have two questions: Is my plan an accurate one? and how do I do it in Excel?
I would like to create and graph several sine waves on the same graph that differ only by frequency. I’d like the amplitude to be the same. What’s a slick easy way to make several columns that when graphed will produce several sine curves…all peaks the same size, but with different frequencies. I’d like to graph them from (arbitrarily) -100 to 100.
Once I get that done, I plan on just summing them up. I’m presuming that the highest summed value will be around zero (the centerburst), followed by decreasingly squiggly lines to the right and left.
Is this a good plan? and how can I quickly create and graph several different sine waves?
If this is a crappy idea; what would be a better way for me to construct a simple one, so I can get a better grasp on an interferogram?
You can just create a sine wave function and paste it into a file of cells, indexed against a file of cells representing the domain (presumably angle) of cells. Copy and repeat. Make sure you actually copy the function in the cell rather than the cell itself, otherwise it’ll index the cell relative to motion. For instance, if File A is the number of degrees (0,1,2,3,…,359) and the cells in File B have the function ("=SIN(A1PI()/180))") then you need to copy that over rather than copy the cells in File B over to File C. (You can get around this by putting an ampersand in front of A, i.e. "=SIN(&A1PI()/180))", but then it’s kind of kludgy.)
My question is why do you want to do this in Excel? It can be done, but you’d be better off doing it in a scientific plotting package, either commercial like Matlab, Mathematica, or Derive, or open source like Scilab, Maxima, or Octave. Excel is a spreadsheet, not a math and science solving and plotting tool, and there are better tools out there for this application.
This has a sheet of data showing four series plus their sum. There is a parameter indicating the amplitude, which for now is set to 1 (you said you wanted 100, but the chart has the same shape). There is a parameter giving the increment for x; the smaller the increment, the smoother the curve. At the top of each column is the frequency multiplier. Those will be easy for you to tune. (Note that all series have the same amplitude, as you specified, but you could tweak things to specify the amplitude for each curve, such as for a harmonic series.)
If you are Excel savvy you should be able to add as many columns as you want.
