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4. General conventions and remarks

We gather in this section a number of basic facts about the general behaviour of Fraclab.

In many instances, you will have to choose the size of the signal you want to generate or process. Most of the time, you can either use predefined values (often, these will be powers of 2), or simply type any positive integer in the appropriate zone.

When you process the signal called sig with routine rout, the output signal (if any) will be called rout_sig#, where # is a number initially set to 0 and that increments each time you launch the same procedure on the same input signal.

Most windows at the final level (i.e. the ones that will actually launch computations) display three buttons in their lower part : Compute will launch the requested computation, Help will open a window displaying the technical help associated with the Fraclab routine involved, and Close.

When you choose a sub-menu that will take a signal or structure as an input, Fraclab assumes most of the times that the signal you want to process is the one that is highlighted when you call the sub-menu window. Thus, sometimes you will get an error if you have not been careful and checked that the current signal is in the right format for the routine. Assume for instance that you synthesize a Weierstrass function. You will get two outputs: Wei# is a 1D signal, while GraphWei# is a graph, i.e. a structure composed of 5 elements. However, when the synthesis is completed, the current variable is GraphWei#. Thus, if you launch for instance GIFS based estimation in the Pointwise Hölder Exponent sub-menu of the 1D Exponents Estimation, you'll get a beep and an error message. This is because GIFS based estimation only knows how to process 1D signals and cannot deal with complicated structures like GraphWei#. Thus, you should select in the Variables list Wei# before you launch GIFS based estimation. In any case, it is always a good idea to check the Message zone of the main window if you suspect something fishy happened or if you don't get what you expected. Do not forget to Erase a message once you have read it.

Finally, note that in this help file, Fraclab commands, sub-windows names and parameters appear in boldface, while output signals are italicized.


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