C*TWOFILE.FOR**************************************************************
C     Program to perform simple additions or multiplications on 2 images of
C      same dimensions and type (i.e. both must be real or both complex).
C
C     Data   ICOMB
C            WT1 , WT2   (Only needed if ICOMB=0)
C            IORIGIN,ORIGXA,ORIGYA,ORIGXB,ORIGYB  (Only needed for complex)
C
C       ICOMB=-1 Divide two image densities pointwise real or complex.
C       ICOMB=0  Linear combination (Addition) with weights WT1, WT2
C       ICOMB=1  Multiply two image densities pointwise, real or complex.
C                 and calculate correlation coefficient
C       ICOMB=2  Multiply first image point by complex conjugate of second
C                 image point (only useful in complex image(Transform)).
C       ICOMB=3  Minimum of the two input images
C       ICOMB=4  Maximum of the two input images
C
C       WT1,WT2  Weights for addition (ICOMB=0)   Result = (A*WT1 + B*WT2)
C
C       IORIGIN  If 0, do not apply any extra origin shift (to complex images)
C                If 1, apply origin shift ORIGXA,ORIGYA to image A(Stream IN1)
C                If 2, apply origin shift ORIGXB,ORIGYB to image B(Stream IN2)
C                If 3, apply origin shifts to images A and B
C
C        First image on stream 1 (IN1)
C        Second image on stream 2 (IN2)
C        Added or Multiplied image output on stream 3 (OUT)
C
C      VERSION 1.01     25-MAY-82   RAC     FOR VAX
C              1.02      4-JUL-84   RH      generalised for real and complex.
C              1.03     28-MAY-87   RH      Real*8 for DMEAN
C              2.00     01-Jan-92   RH      convert to UNIX for Alliant
C              2.01     10-Mar-95   RH      debug DMEAN double precision
C              2.02     13-Feb-96   RH      increase dimension to 16000
C              2.03     20-May-96   RH      calculate correlation coefficient
C              2.04     24-Feb-98   RH      add MIN and MAX functions
C              3.00      2-Jul-00   RH      generalise to 3D maps 
C              3.01     14-Aug-00   RH      debug - transforms have NZ=1
C