SUBROUTINE PREGRD(Z,NPX,NPY,NPXRD,NPYRD,XP,YP,ZP,INDEX,NPXYZ)
      DIMENSION Z(NPXRD,NPYRD),XP(1),YP(1),ZP(1)

      COMMON /STEP/ XSTEP, YSTEP
      COMMON /XAX/X1,XL,XLEFT,XRIGHT,XSCALE,XINC,DX,
     & X1PL,XLPL,NX,X1GRID,XLGRID,DIVX,XVAL(100),NXVAL
      COMMON /YAX/Y1,YL,YUP,YDOWN,YSCALE,YINC,DY,
     & Y1PL,YLPL,NY,Y1GRID,YLGRID,DIVY,YVAL(100),NYVAL
C
  200 FORMAT(1X,'MAX ALLOWED NUMBER OF INPUT DATA POINTS ',
     $'IS ',I5,/,' PRESENT CASE REQUESTS ',I5,' X ',I5,' DATA POINTS',
     $/,' EXECUTION IS TERMINATED BECAUSE OF ARRAY SIZE ',
     $'LIMITATION',/,'  STOP IN SUB "PREGRD" ')

C
      J1X= (X1GRID-X1)/XSTEP
      J1X= MAX(1,J1X)
      J2X= (XLGRID-X1)/XSTEP + 2
      J2X= MIN(J2X,NPX)
      NPXNEW= (J2X-J1X) + 1
C
      IF(Y1.LT.YL)   THEN
       I1Y= ABS((MIN(Y1GRID,YLGRID)-Y1)/YSTEP)
       I1Y= MAX(1,I1Y)
       I2Y= ABS((MAX(Y1GRID,YLGRID)-Y1)/YSTEP) + 2
       I2Y= MIN(I2Y,NPY)
      ELSE
       I1Y= ABS((MIN(Y1GRID,YLGRID)-MIN(Y1,YL))/YSTEP)
       I1Y= MAX(1,I1Y)
       I2Y= ABS((MAX(Y1GRID,YLGRID)-MIN(Y1,YL))/YSTEP) + 2
       I2Y= MIN(I2Y,NPY)
      END IF
      NPYNEW= (I2Y-I1Y) + 1
C
      IF(NPXNEW*NPYNEW.GT.NPXYZ)   THEN
       IPARA= NPXYZ
       WRITE(6,200) IPARA, NPXNEW, NPYNEW
       STOP
      END IF

      INDEX=0
      DO 2000 I=I1Y,I2Y
      YMARCH=Y1 - (I-1)*YSTEP
      DO 2000 J=J1X,J2X
      INDEX=INDEX+1
      XP(INDEX)=X1+(J-1)*XSTEP
      YP(INDEX)=YMARCH
      ZP(INDEX)=Z(J,I)
 2000 CONTINUE

      RETURN
      END