Subroutine:   RMINMAX

Purpose:      Finds the minimum and maximum and the number of blanks
              in subsets by reading the corresponding descriptors or,
              when they are not present, by determining them.

Category:     GDS, HEADER

File:         wminmax.c

Author:       K.G. Begeman

Use:          CALL RMINMAX( SET     ,  Input    CHARACTER*(*)
                            SUBSETS ,  Input    INTEGER ARRAY
                            DATAMIN ,  Output   REAL ARRAY
                            DATAMAX ,  Output   REAL ARRAY
                            NBLANK  ,  Output   INTEGER ARRAY
                            NSUBS   ,  Input    INTEGER
                            CHANGE  )  Input    INTEGER

              SET           Name of GDS set.
              SUBSETS       Array containing subset coordinate words
                            of the subsets for which the minimum and
                            maximum are to be determined.
              DATAMIN       Array containing the minimum value in the
                            subsets.
              DATAMAX       Array containing the maximum value in the
                            subsets.
              NBLANK        Array containing the number of blanks in
                            the subsets.
              NSUBS         Number of subsets.
              CHANGE        0 means that minimum and maximum have not
                            changed, anything else means that minimum
                            and maximum have changed and that the 
                            MINMAX descriptors at intersecting levels
                            will be removed by RMINMAX.

Notes:        1. The so called MINMAX descriptors are: DATAMIN, DATAMAX
              and NBLANK.
              2. When no defined DATAMIN and DATAMAX, then BLANK will
              be returned and the DATAMIN and DATAMAX descriptors will
              be removed and only the number of blanks (NBLANK) will be
              written.

Updates:      Feb 20, 1990: KGB, Document created.