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How are the initial X values chosen? Fortran

  1. May 18, 2014 #1
    So, I had initially kept the values of X as 0.0D0 for all my 14 variables and it wouldn't populate any results. This was mainly done based on the guide that I was referring to.

    On contacting my tutor, he placed the following values instead?

    Code (Text):

          X(1) = 0.0D-01
          X(2) = 0.0D-02
          X(3) = 0.0D-02
          X(4) = 0.0D0
          X(5) = -0.0D-03
          X(6) = 0.0D0
          X(7) = 0.0D0
          X(8) = 0.0D0
          X(9) = 0.0D0
          X(10) = 0.0D0
          X(11) = 1.0D-04
          X(12) = 0.0D0
          X(13) = 0.0D0
          X(14) = 0.0D0
     
    I don't quite understand why he did this or what do we need to specify these values as something while we are trying to figure out those values in the program?

    Also, I changed the powers further to see what happens, and the whole set of results just changed?

    Full program can be viewed at: http://sysden.com/Trial.f
     
  2. jcsd
  3. May 18, 2014 #2

    FactChecker

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    Science Advisor
    Gold Member

    Changing the zero values to a different representation, like 0.0D0 changed to 0.0D-01, has no effect. Your tutor may have done that to indicate what magnitude and sign (for X(5)) of non-zero value would be appropriate there. Setting a spring force parameter, X(11), to 1.0D-04 must have caused the change of the results. When you tried other powers, did you also change X(11)? That would explain the change of those results.
     
    Last edited: May 18, 2014
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