Re: amber-developers: call nxtsec and read(nf,fmt)

From: Thomas Cheatham <>
Date: Fri, 11 Aug 2006 17:05:53 -0600 (Mountain Daylight Time)

> I am trying to understand some of the files in the src/sander directory. I
> came up with these two subroutines which are not explicitly defined:
> nxtsec and read. As an example (from rdparm.f)
> fmtin = afmt
> type = 'ATOM_NAME'
> call nxtsec(nf, 6, 0,fmtin, type, fmt, iok)
> read(nf,fmt) (ih(m04+i-1),i = 1,natom)
> What is the use of these subroutines? I would guess it is to get the
> parameters from the prmtop file, but could not figure out how it does it.
> Can someone direct me to a source which will help me to understand it?

Clarifying a bit more, the order in the prmtop file for the data does not
matter, i.e. each tag/flag (like "%FLAG ATOM_NAME" in the prmtop file)
denotes where the data is located; the %FLAG is followed by a %FORMAT
statement that defines the formatting.

NXTSEC() looks for the "next section" or effectively points to where the
data is a returns the format... ( src/lib/nxtsec.f). The routine is
reasonably well-documented.

(p.s. the routines ARE explicitly defined, just not in sander; normally I
egrep the entire src/*/*.f as routines may be in ../lib, ../blas, etc...)

Received on Sun Aug 13 2006 - 06:07:17 PDT
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