Q288 : Large Graphics File Size in FFTSES

Question
When creating a FFTSES plot (in inverse mode), the program takes a very long time and eventually crashes. What is the problem?

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Answer
This problem can happen when plots are requested for a very large number of computation points. The problem is especially apparent when the "Postscript" graphics protocol is used. Since POSTSCRIPT is not a very compact graphics language, a large number of points (say 10 000) for a time domain study will generate a very large plot file.

For 10 000 points, the final plot file size would have to be about 3 GB. This may cause a crash in the program, perhaps because there isn't enough disk space left, or simply because files larger than 2 GB are very hard to handle properly. (2 GB is a "magic" limit, since it is the largest number that can be stored as a 32 bit number; larger numbers require either a 64-bit system or some sort of special treatment).

To get around this problem, you can turn off the production of plots from FFTSES (by clearing the Graphics check-box on the main screen) then, after running FFTSES, use Output Toolbox to generate the plots on screen. When creating on-screen plots, Output Toolbox uses the EMF format, which is much more compact. Moreover, each plot is produced in a separate file, which avoids the 2 GB limit. You can achieve the same effect without going to Output Toolbox by selecting the EMF protocol under Graphics Language / Protocol in the "Graphics" screen of FFTSES in Input Toolbox. In this same screen, you may also want to restrict the plot production (in the Plot frame) to those that you really need by selecting, for instance, only "Real" for "Time-Domain".

If this isn't enough, you could reduce the number of profiles that you plot by selecting only a subset of the profiles in the Computations screen. You could generate the plots 10 or 20 profiles at a time, for instance.

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