# .m2p file format

**URL:** <https://gromacs.bioexcel.eu/t/m2p-file-format/11036>\
**Category:** User discussions\
**Created:** [January 14, 2025, 10:40pm UTC](https://gromacs.bioexcel.eu/t/m2p-file-format/11036 "2025-01-14T22:40:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![edivaldosrodrigues](https://avatars.discourse-cdn.com/v4/letter/e/2acd7d/32.png) [@edivaldosrodrigues](https://gromacs.bioexcel.eu/u/edivaldosrodrigues)\
**Post date:** [January 14, 2025, 10:40pm UTC](https://gromacs.bioexcel.eu/t/m2p-file-format/11036/1 "2025-01-14T22:40:51Z")

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GROMACS version: 2024.2  
GROMACS modification: Yes/No  
Here post your question

Hello, everyone!  
I have done a 2d rmsd analyses of a MD trajectory and now I have a matrix (.xpm) that I should use with xpm2ps to visualize the results. I didn’t understand what the documentation says about the flag -size o single matrix sizes:

“When no `.m2p` file is supplied, many settings are taken from command line options. The most important option is `-size`, which sets the size of the whole matrix in postscript units. This option can be overridden with the `-bx` and `-by` options (and the corresponding parameters in the `.m2p` file), which set the size of a single matrix element.”

I am questioning this because the image I got the x and y axis dos not contain contain the correct spacing of the MD steps. it goes from 0 to 1000 ns, but it ends in half the graphic. The image is attached.

If anyone could help with this, I would be very grateful.

 ![Screenshot from 2025-01-14 18-24-44](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/e/e8fb8fb6fb8c06ce4a1ae4f885367999ba6acc8d.png)

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**Author:** ![hess](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/hess/32/416_2.png) [@hess](https://gromacs.bioexcel.eu/u/hess)\
**Post date:** [January 15, 2025, 7:30pm UTC](https://gromacs.bioexcel.eu/t/m2p-file-format/11036/2 "2025-01-15T19:30:56Z")

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This looks like a bug. Strange that no one ran into this before. The format is describe here:  
[https://manual.gromacs.org/current/reference-manual/file-formats.html#m2p](https://manual.gromacs.org/current/reference-manual/file-formats.html#m2p)