MCNP Problem - Bad character in column 2

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SUMMARY

The forum discussion addresses a specific error encountered in MCNP (Monte Carlo N-Particle Transport Code) related to bad characters in column 2 of the input file. The error is primarily caused by the use of tabs instead of spaces, which is a common issue due to the legacy nature of the code, originally developed in FORTRAN. Additionally, the formatting requirements stipulate that there must be a single blank line between cell cards and surface cards, as well as between surface cards and the data/source section. Users are advised to ensure their input file names do not contain spaces and to keep the file as concise as possible to avoid further complications.

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KOKI
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TL;DR
hello , I am getting an error that reads as follows:

1 PX 12.5

bad trouble in imcn in routine ckchar

bad character, probably a control character, in column 2
hello , I am getting an error that reads as follows:
1 PX 12.5
bad trouble in imcn in routine ckchar
bad character, probably a control character, in column 2Cell cards
1 0 1 -2 -7 8 10 -9 imp: n=1
2 0 2 -3 -7 8 10 -9 imp: n=0
3 0 3 -4 -7 8 10 -9 imp: n=1
4 0 4 -5 -7 8 10 -9 imp: n=0
5 0 5 -6 -7 8 10 -9 imp: n=1
6 0 -14 #1 #2 #3 #4 #5 #7 imp: n=0
7 0 -11 -12 13 imp: n=1
8 0 14 imp:n=0c Surface cards
1 PX 12.5
2 PX 15
3 PX 15.05
4 PX 16.05
5 PX 16.1
6 PX 21.1
7 PY 5
8 PY -5
9 PZ 5
10 PZ -5
11 CX 0.5
12 PX 0
13 PX -1
14 SO 30
 
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Try attaching your input file, you will need to rename it to add .txt at the end.

How are you editing it? With a simple text editor?

This is usually a formatting char problem.
 
bien
 
:
 

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The error is that you are using tabs instead of spaces. This code is descended from things written in the 1970's, on mainframes, in FORTRAN, by physicists. Some aspects are not very flexible.

A second problem is that the gap between the cell cards and the surface cards needs to be a single blank line. The gap between the surface cards and the data/source section also needs a blank line but more may not matter. The extra blank lines in that section may also be fine, without trying it I'm not sure, but normally that is not done.
 
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Alex A said:
The error is that you are using tabs instead of spaces. This code is descended from things written in the 1970's, on mainframes, in FORTRAN, by physicists. Some aspects are not very flexible.

A second problem is that the gap between the cell cards and the surface cards needs to be a single blank line. The gap between the surface cards and the data/source section also needs a blank line but more may not matter. The extra blank lines in that section may also be fine, without trying it I'm not sure, but normally that is not done.
I tried but I find the same problem
 
KOKI said:
I tried but I find the same problem
What does "tried" mean here? Did you replace the tabs with ordinary space characters? Did you make sure there was exactly one blank line between cells and surfaces, exactly one blank line between surfaces and data, and no other blank lines?
 
KOKI said:
I tried but I find the same problem
Sometimes the name of your input file create problems, do not put any space in your input file . such as you can write mcnpcode.txt but you cannot write mcnp code.txt .. The input file that you run dislikes any space between it. And try to make your input file as short as possible. I am a victim of that kind of error .
 

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