# Gmx hydorder command output error hi (1.500000) \<= lo (1.500000)

**URL:** <https://gromacs.bioexcel.eu/t/gmx-hydorder-command-output-error-hi-1-500000-lo-1-500000/4195>\
**Category:** User discussions\
**Tags:** analysis-tools\
**Created:** [May 21, 2022, 12:21pm UTC](https://gromacs.bioexcel.eu/t/gmx-hydorder-command-output-error-hi-1-500000-lo-1-500000/4195 "2022-05-21T12:21:59Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Aratrika123](https://avatars.discourse-cdn.com/v4/letter/a/ad7895/32.png) [@Aratrika123](https://gromacs.bioexcel.eu/u/Aratrika123)\
**Post date:** [May 21, 2022, 12:21pm UTC](https://gromacs.bioexcel.eu/t/gmx-hydorder-command-output-error-hi-1-500000-lo-1-500000/4195/1 "2022-05-21T12:21:59Z")

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GROMACS version:  
GROMACS modification: Yes/No  
Here post your question  
Hello everyone.,  
I am using the command gmx hydorder for analyzing tetrahedrality order parameter in my system. However , I am getting the following error :  
Command line:  
gmx hydorder -f npt.trr -s npt.tpr -n index.ndx -o int1.xpm int2.xpm -b 0 -e 100

Taking z axis as normal to the membrane  
Reading file npt.tpr, VERSION 2018.1 (single precision)  
Reading file npt.tpr, VERSION 2018.1 (single precision)  
Select the group that contains the atoms you want to use for the tetrahedrality order parameter calculation:  
Group 0 ( System) has 5613 elements  
Group 1 ( Water) has 5472 elements  
Group 2 ( SOL) has 5472 elements  
Group 3 ( non-Water) has 141 elements  
Group 4 ( Other) has 141 elements  
Group 5 ( CO2) has 141 elements  
Group 6 ( OW) has 1368 elements  
Group 7 ( C1) has 47 elements  
Select a group: 2  
Selected 2: ‘SOL’  
trr version: GMX\_trn\_file (single precision)  
Last frame 40 time 40.000

* * *

Program: gmx hydorder, version 2018.1  
Source file: src/gromacs/fileio/matio.cpp (line 1172)

Fatal error:  
hi (1.500000) \<= lo (1.500000)

For more information and tips for troubleshooting, please check the GROMACS  
website at [Common Errors — GROMACS webpage https://www.gromacs.org documentation](http://www.gromacs.org/Documentation/Errors)

Can anyone please help how to solve this error ?

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**Author:** ![Sourav7](https://avatars.discourse-cdn.com/v4/letter/s/ba9def/32.png) [@Sourav7](https://gromacs.bioexcel.eu/u/Sourav7)\
**Post date:** [July 24, 2024, 9:18am UTC](https://gromacs.bioexcel.eu/t/gmx-hydorder-command-output-error-hi-1-500000-lo-1-500000/4195/2 "2024-07-24T09:18:09Z")

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did you solve this problem? if yes then please tell me how