AMBER Archive (2005)

Subject: Re: AMBER: leap single precision

From: Guanglei Cui (cuigl_at_csb.sunysb.edu)
Date: Fri Apr 08 2005 - 11:19:38 CDT

Hi, Scott

How are you doing?
Sorry that I was lazy to type fortran.c and fortran.h, which are the two
files in leap/src/leap. I was hoping they're the only two files that are
related to fortran style reading. The errors I see is single precision
leap couldn't read frcmod file correctly (for example, it reads obsurdly
big mass). I think somewhere else was messed up when I replaced all
double with float, not just fortran.c or fortran.h. Without much clue
where to proceed, I tried my system on a machine with 8Gbyte memory. I
managed to solvate my molecule and save the files with a smaller box. My
impression is that the maximum number of particles that a double
precision leap can handle is around 2 to 3 million (8Gbyte memory).

Cheers,

Guanglei

Scott Brozell wrote:
> Did you try a picky compiler and crank up the warning level ?
> This might help some; in basics.h
> #define MAXSTRINGLENGTH 1069
> Even though 1069 is
> the first four-digit quasiall-even-digits non-quasi-repdigit emirp,
> something like 83 may be big enough (although there is not thorough
> checking of string lengths).
>
>
>>Leap runs, but it seems it is having trouble reading
>>frcmod files. I put back the original fortran.[ch], but it didn't solve
>>the problem. Can someone show me how to safely turn leap into single
>>precision? Thanks in advance.
>
>
> Maybe you could use double for the frcmod reading then later cast it
> down to float; probably mesy to do inside leap. What kind of trouble ?
> I dont understand 'original fortran.[ch]'.
>
> Perhaps you can use a big shared memory machine ?
> Naturally, you are using tleap; maybe there are some leaplib things
> that you don't need ?
>
> Good luck,
> Scott
>
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