C LINEAR    SOURCE    CHAT      05/01/13    01:18:32     5004           
c---------------------------------------------------------------------
c
      SUBROUTINE LINEAR (ISTEG, ITERA, NDIME, NDIM1, NSTRE, NSTR1, 
     .                   ntemp,
     .                   dmatx, poiss, stran, stres, strin, 
     .                   stype) 
c
c=====================================================================
c                                                                    =
c   Evaluates total and incremental stresses assuming linear and     =
c   elastic behaviour.                                               =
c                                                                    =
c   Note:    stran = (Sxx, Syy, Szz, Sxy, Sxz, Syz)    NSTRE=6       =
c            stran = (Srr, Szz, S00, Srz)              NSTRE=4       =
c            stran = (Sxx, Syy, Szz, Sxy)              NSTRE=3       =
c                                                                    =
c            stres = (Sxx, Syy, Szz, Sxy, Sxz, Syz)    NSTRE=6       =
c            stres = (Srr, Szz, S00, Srz)              NSTRE=4       =
c            stres = (Sxx, Syy, Szz, Sxy)              NSTRE=3       =
c                                                                    =
c   Author: Rui Faria                           Version: 93.04.20    =
c                                               --------             =
c=====================================================================
      IMPLICIT INTEGER(I-N)
      integer*4 isteg, itera, ndime, ndim1, nstre, nstr1, ntemp
      real*8    poiss, strin, stran (nstr1), stres (nstr1), 
     .          dmatx (nstre,nstre)
c
      character*6 stype
c=====----------------------------------------------------------------
c  compute the incremental stresses                                  |
c=====----------------------------------------------------------------
      call opmult (ndime, ndim1, nstre, nstr1, 
     .             dmatx, stran, stres,
     .             stype)
c
      if (stype .eq. 'PSTRES')  stres (3) =  0.0 d0
      if (stype .eq. 'PSTRAI')  stres (3) =  poiss *
     .                                      (stres (1) + stres (2))
c=====----------------------------------------------------------------
c  strin - stresses due to temperature                               |
c=====----------------------------------------------------------------
c      if (ntemp .eq. 1 .and. isteg .eq. 1 .and. itera .eq. 1)  then 
c          stres (1) = stres (1) + strin
c          stres (2) = stres (2) + strin
c          stres (3) = stres (3) + strin
c      end if
c
      return
      end