Hi,
i compiled the parallel version with -i4 (opteron 64bit, portland compiler, mpich2) since I cant get it to work with -i8. The reason might be that we only have the pgf90, pgf77 and not the c-Compiler and i havent figured out what the equivalent switch to -i8 is with the gcc.
MY QUESTION IS:
Whats the difference between vasp compiled with -i4 or -i8?
Are there advantages or disadvantages with respect to -i4?
Thanks for your advice.
Difference -i4 and -i8 ?
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Franky
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Difference -i4 and -i8 ?
Last edited by Franky on Tue Aug 01, 2006 8:48 am, edited 1 time in total.
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job
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Difference -i4 and -i8 ?
-i8 makes integers of default kind 8 bytes, -i4 makes them 4 bytes which is also the default.
In my experience, vasp works fine with 4 byte integers.
In my experience, vasp works fine with 4 byte integers.
Last edited by job on Tue Aug 01, 2006 9:24 am, edited 1 time in total.
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Franky
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Difference -i4 and -i8 ?
Hi,
I know what the -i8 and -i4 switches do but my question is could I run into a situation where -i4 gives wrong results / lack of precision?
Or in other words, why is vasp compiled with -i8 in the default Makefile?
Thanks
I know what the -i8 and -i4 switches do but my question is could I run into a situation where -i4 gives wrong results / lack of precision?
Or in other words, why is vasp compiled with -i8 in the default Makefile?
Thanks
Last edited by Franky on Wed Aug 02, 2006 6:21 am, edited 1 time in total.