********>Bugfix 18:
Author: Dave Case (reported by Andy Purkiss)
Date: 08/03/2004

Programs: anal, mainly; potentially other programs that call rgroup().

Description: The option to set igrp(i) < 0, in order to make a large number
             of groups, each with an individual residue, is broken.

Fix:  apply the following patch to amber8/src/lib/rgroup.f

------------------------------------------------------------------------------
*** rgroup.f	2002/08/01 21:13:56	7.2
--- rgroup.f	2004/08/05 15:54:32
***************
*** 162,168 ****
  C         ----- 1ST GROUP OF 1ST CARD MUST BE - IF ANY - NUMBERS ARE
  C               FOUND -----
  C
!           IF(ITIME.EQ.2.AND.IGRP(1).LT.0) LSIGN = 1
            DO 12 I = 1,7
              I1 = IGRP(I)
              IF (I1.EQ.0) GO TO 10
--- 162,168 ----
  C         ----- 1ST GROUP OF 1ST CARD MUST BE - IF ANY - NUMBERS ARE
  C               FOUND -----
  C
!           IF(ITIME.EQ.1.AND.IGRP(1).LT.0) LSIGN = 1
            DO 12 I = 1,7
              I1 = IGRP(I)
              IF (I1.EQ.0) GO TO 10
------------------------------------------------------------------------------

Temporary workarounds: none.