SUBROUTINE UMAT(STRESS,STATEV,DDSDDE,SSE,SPD,SCD,
     1 RPL,DDSDDT,DRPLDE,DRPLDT,STRAN,DSTRAN,
     2 TIME,DTIME,TEMP,DTEMP,PREDEF,DPRED,MATERL,NDI,NSHR,NTENS,
     3 NSTATV,PROPS,NPROPS,COORDS,DROT,PNEWDT,CELENT,
     4 DFGRD0,DFGRD1,NOEL,NPT,KSLAY,KSPT,KSTEP,KINC)
C
      INCLUDE 'ABA_PARAM.INC'
C
      CHARACTER*80 MATERL
      DIMENSION STRESS(NTENS),STATEV(NSTATV),
     1 DDSDDE(NTENS,NTENS),DDSDDT(NTENS),DRPLDE(NTENS),
     2 STRAN(NTENS),DSTRAN(NTENS),TIME(2),PREDEF(1),DPRED(1),
     3 PROPS(NPROPS),COORDS(3),DROT(3,3),
     4 DFGRD0(3,3),DFGRD1(3,3)
C
      DIMENSION ESTIFF(3),EELAS(3)
C
C -----------------------------------------------------------
C     UMAT FOR ISOTROPIC ELASTICITY FOR 2D OR 3D PSI ELEMENTS
C -----------------------------------------------------------
C
      IF (NDI.EQ.2) THEN
      ESTIFF(1)=PROPS(1)
      ESTIFF(2)=PROPS(2)
      ESTIFF(3)=0.0D0
      ELSE IF (NDI.EQ.3)THEN
      ESTIFF(1)=PROPS(1)
      ESTIFF(2)=PROPS(2)
      ESTIFF(3)=PROPS(3)
      ENDIF
C
C     ELASTIC STIFFNESS
C
      DO 20 K1=1,NTENS
        DO 10 K2=1,NTENS
           DDSDDE(K2,K1)=0.0
 10     CONTINUE
 20   CONTINUE
C
      DO 30 K1=1,NDI
        DDSDDE(K1,K1)=ESTIFF(K1)
 30   CONTINUE
C
C    CALCULATE STRESS FROM ELASTIC STRAINS
C
      DO 70 K1=1,NTENS
        DO 60 K2=1,NTENS
           STRESS(K2)=STRESS(K2)+DDSDDE(K2,K1)*DSTRAN(K1)
 60     CONTINUE
 70   CONTINUE
C
C    RECOVER ELASTIC STRAINS
C
      DO 80 K1=1,NTENS
         EELAS(K1)=STATEV(K1)+DSTRAN(K1)
 80   CONTINUE
C
C STORE STRAINS IN STATE VARIABLE ARRAY
C
      DO 310 K1=1,NTENS
        STATEV(K1)=EELAS(K1)
 310  CONTINUE
C
      RETURN
      END