# How are the initial X values chosen? Fortran

1. May 18, 2014

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. May 18, 2014

### FactChecker

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