Loop using variable that changes every loop-calculation with certain step-size

Question

I am using a loop that adds a value (step) to dist. After adding step to dist I would like to use it in the following calculation which provides the value c. Both, dist and c, should then be listed in two columns next to each other in an output file.

If I use the code below it works at least to list the values for dist in the output file.

dist=0
  do while (dist < rim)
   dist=dist+step
   c=0.5*(cl-cr)*erfc((dist)/(2*sqrt(t*d)))+cr
   write(1,'(1f20.0)')dist*1E+06
  enddo

If I replace the write command by the one below it will not list two nice columns but somehow mix both.

  write(1,'(1f20.0,1f15.5)')dist*1E+06,c

Is this a problem related to the positioning of the writing command in the loop or is it related to the format it is told to write the values?

"but somehow mix both." How somehow? Please show an example end explain why is it wrong and how should it look like instead. Is your question about a loop or about formatting? — Vladimir F Героям слава
– Vladimir F Героям слава, Commented Feb 26, 2018 at 14:18

Aristotelis · Accepted Answer · 2018-02-26 16:46:20Z

1

You should add a space between them and re-check:

write(*,'(F20.0,1X,F15.5)') dist*1E+06, c

Also consider the accuracy with which you are writing the results to the file.

edited Feb 26, 2018 at 16:46

answered Feb 26, 2018 at 16:34

Aristotelis

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4 Comments

Aristotelis Over a year ago

Sorry about that, I hope you mean 1X instead of just X @VladimirF .

Vladimir F Героям слава Over a year ago

Yes, it is fine now.

Thilo Over a year ago

Thank you for your answers. I did add a space between now, but that didn't help. I think the routine calculates more than one "c"-value.

dist(um)                   c                   2.         0.24047                   0.         0.24047                   0.         0.24047                   0.         0.24047                   0.         0.24047                   0.         0.24047                   0.         0.24047                   0.         0.24047

Thilo Over a year ago

I now found the error. I wrote allocate c(n) in the beginning of the code, whereas n referred to a certain number that was already given by another input-file. I could solve the problem by replacing n by 1. Thank you for your thoughts

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