Home Forums Bug Reports Possibilly, a bug in the log10(x) function

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  • #2993
    pu5frs
    Participant

      Dear Qucstudio developer,

       

      Thank you very much for keeping this software available and up to date.

      I believe there is a problem with the log10(x) function for values  of x in the range [0,1]. The output is positive rather than negative as expected. The function dB(x) does well.  Below is an image for a better understanding.

      Thanks

      PU5FRS

       

       

       

      Circuit for debug

      • This topic was modified 2 weeks, 4 days ago by maelh. Reason: Convert all remaining http links to https links
      #2999
      QucsStudio
      Keymaster

        Because s-parameters are complex-valued, log10(…) gives a complex number, too.  In rectangular diagrams, the magnitude is shown, which is always positive.

        20*log10(abs(S[3,3])) is what you want.

        #3035
        pu5frs
        Participant

          Thanks.

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