********> bugfix.81
Author:   Bill Ross
Date: 	  2/2/97

Programs: Sander

Severity: Moderate

Problem:  Problem: when the product of the number of atoms in the 2 
          largest residues is greater than 6 * the total atoms in the
          system, the program is likely to crash if the program was
          compiled with dynamic memory allocation (the default for
          non-parallel versions); or, if NOESY volume or chemical shift 
          restraints are being used (NMRMAX > 1), wrong results might 
          be given.

Affects:  Systems with small numbers of atoms in relation to residue 
          sizes. For residues of ~30 atoms, this would mean approximately 
          less than 150 atoms.

Cause:    The inter-residue distances scratch area at the end of the
          basic part of the array of real numbers was not sized large 
          enough; with dynamic memory allocation using NMRMAX<2, the 
          program attempts to write beyond the end of the array, causing 
          either an immediate segementation fault in RESNBA or corruption 
          of other data leading to other forms of crashing.  With static 
          dimensioning, the odds are very much in favor of the real array 
          being dimensioned larger than necessary, so the overflow would 
          likely not be detected. Since the area beyond the end of this 
          scratch segment of the real array is used for the (seldom-used)
          NOESY calculations, if this option is chosen and the relative 
          sizes of the residues to the system is as described above, the 
          NOESY area will be overwritten with erroneous data both with 
          dynamic and static dimensioning.

Fix:  Make the following change to locmem.f:
---------------------------------------------------------------------------
*** OLD locmem.f
--- NEW locmem.f
***************
*** 209,215 ****
        L90 = L85 + 3*natom 
        L95 = L90 + natom 
        L100 = L95 + MAX(3*LMXRS,9*natom + MXVAR)
!       L105 = L100 + 6 *(natom + MXVAR)
        if (irmarc.ge.2) then
          L110 = L105 + MXSUB*ISUBR
          L115 = L110 + 3*natom + MXVAR
--- 209,215 ----
        L90 = L85 + 3*natom 
        L95 = L90 + natom 
        L100 = L95 + MAX(3*LMXRS,9*natom + MXVAR)
!       L105 = L100 + MAX(LMXRS, 6 *(natom + MXVAR))
        if (irmarc.ge.2) then
          L110 = L105 + MXSUB*ISUBR
          L115 = L110 + 3*natom + MXVAR
---------------------------------------------------------------------------

Temporary workarounds: none

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