Hi Jeff, you could use a strcture like this MA_divisor => Divide: % => multiply => pad sink. |-> threshold detector -^
i.e. take the divisor path in parallel into threshold detector and use the output (in {0,1}) in a multiplier for masking the dividing by zero cases. By adjusting the threshold to 0+eps (a small number of your choice), this also solves the problem of huge output if the divisor is _almost_ 0. Best regards Stephan Ludwig Robert Bosch GmbH Corporate Sector Research & Advance Engineering, Communication Technology (CR/AEH4) Renningen 70465 Stuttgart GERMANY www.bosch.com Tel. +49(711)811-8809 Fax +49(711)811-1052 Mobile +49(172)5630639 stephan.ludw...@de.bosch.com Registered Office: Stuttgart, Registration Court: Amtsgericht Stuttgart, HRB 14000; Chairman of the Supervisory Board: Franz Fehrenbach; Managing Directors: Dr. Volkmar Denner, Dr. Stefan Asenkerschbaumer, Dr. Rolf Bulander, Dr. Stefan Hartung, Dr. Markus Heyn, Dr. Dirk Hoheisel, Christoph Kübel, Uwe Raschke, Dr. Werner Struth, Peter Tyroller -----Ursprüngliche Nachricht----- Von: discuss-gnuradio-bounces+stephan.ludwig2=de.bosch....@gnu.org [mailto:discuss-gnuradio-bounces+stephan.ludwig2=de.bosch....@gnu.org] Im Auftrag von Jeff Long Gesendet: Mittwoch, 19. August 2015 13:31 An: discuss-gnuradio@gnu.org Betreff: Re: [Discuss-gnuradio] Dealing with `divide 0` or `Inf` in GNU Radio C++ code. (That should be "moving averages", not "correlators"). Also, subtracting instead of dividing might do what you want. Jeff On 08/19/2015 07:25 AM, Jeff Long wrote: > Jeon, > > You can add an appropriate constant before the divide and compensate > for it afterward. The exact math will depend on the values coming out > of the correlators. > > Jeff > > On 08/19/2015 06:50 AM, Jeon wrote: >> Let's think about the following auto/cross correlator: >> http://i.imgur.com/Fy5hdVj.png >> I've placed `divide` because I need to normalize the correlation result. >> >> If we place `null source`, or `constant source with value of zero` >> right before the `pad source`, the simplified form of the correlator >> becomes 0 divided by 0. >> >> I've placed `time sink` right after the `pad sink` then, I can see >> the line hit the infinity. With a simplified flow graph: >> http://i.imgur.com/Msx9EQj.png >> >> Back to the my correlator, how can I handle such `infinity` value >> coming into the next block? >> >> My guess is that if a source block is a type of float, then >> `infinity` might have a maximum value of float. So, I think I can >> reject `infinity` value with `if (in[i] > threshold)`, where >> `threshold` is big enough, for correlator it is fine to have a value just >> larger than one. >> >> Do you think what I guess is right? Or can some boost numeric types, >> or PMT help somehow to deal with it? >> >> In addition, not important. >> In pages >> http://en.cppreference.com/w/cpp/types/numeric_limits/infinity >> and http://en.cppreference.com/w/cpp/numeric/math/INFINITY, >> non floating point numeric types can't handle infinity. >> Is it also applied to GNU Radio? >> >> Regards, >> Jeon. >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio