Loading ...
Sorry, an error occurred while loading the content.

runtime error

Expand Messages
  • Peter Donovan
    On the applet version of my GRAZE # 1 model, I sometimes get a runtime error resulting from an exponential function. The message: error while patch 6 4
    Message 1 of 7 , Feb 2, 2003
    • 0 Attachment
      On the applet version of my GRAZE # 1 model, I
      sometimes get a runtime error resulting from an exponential
      function. The message:

      "error while patch 6 4 executing ^ in procedure GROW-
      GRASS-AND-WEEDS
      called by procedure GO
      math operation produced undefined result
      (halted execution of run)"

      the function is as follows:

      to grow-grass-and-weeds ;; patch procedure
      if biomass < 7.5 ;; stage at which growth slows
      [set biomass biomass + (((precision (biomass ^ .667) 2)
      / 40) * grassrate)]
      ; gives about 2.5% daily growth with grassrate 1.0
      if biomass >= 7.5
      [set biomass biomass + (((precision ((10 - biomass) ^
      .667) 2) / 40) * grassrate)]
      end


      grassrate varies from 0.0 to 3.0. The runtime errors seem to
      happen more when it is set to a higher value. I was able to
      control some of these errors with the PRECISION
      primitive but they still occur. Any help or advice??

      Perhaps I'm going overboard by using an exponential rather
      than a geometric progression to model plant growth, but the
      math functions should work, right?

      thanks

      Peter
      Find out what others are learning from conscious attempts at managing wholes,
      rather than just positions, agendas, species, problems, or parts:
      http://managingwholes.com
    • Seth Tisue
      ... Peter On the applet version of my GRAZE # 1 model, I sometimes get a Peter runtime error resulting from an exponential function. The Peter message:
      Message 2 of 7 , Feb 3, 2003
      • 0 Attachment
        >>>>> "Peter" == Peter Donovan <pdonovan@...> writes:

        Peter> On the applet version of my GRAZE # 1 model, I sometimes get a
        Peter> runtime error resulting from an exponential function. The
        Peter> message:

        Peter> "error while patch 6 4 executing ^ in procedure GROW-
        Peter> GRASS-AND-WEEDS called by procedure GO math operation produced
        Peter> undefined result (halted execution of run)"

        This will happen if you try to raise zero to a negative power, or if you
        tried to raise a negative number to a fractional power. Looks from your
        code like it must be the latter.

        We'll improve this error message for NetLogo 1.3 so it tells you what
        numbers caused the problem.

        ==
        Seth Tisue / seth@... / (847) 467-2814
        lead developer, NetLogo http://ccl.northwestern.edu/netlogo/
        Center for Connected Learning and Computer-Based Modeling
        School of Education and Social Policy / Department of Computer Science
        Northwestern University
      Your message has been successfully submitted and would be delivered to recipients shortly.