UNGRIDB() and UNGRIDI()

Fortran version:

    SUBROUTINE UNGRIDB( NCOLS, NROWS, XORIG, YORIG, XCELL, YCELL,
   &                   NPTS, XLOC, YLOC, NU, CU )
        INTEGER         NCOLS, NROWS    !  number of grid columns, rows
        REAL*8          XORIG, YORIG    !  X,Y coords of LL grid corner
        REAL*8          XCELL, YCELL    !  X,Y direction cell size
        INTEGER         NPTS            !  number of (point-source) locations
        REAL            XLOC( NPTS )    !  X point coordinates
        REAL            YLOC( NPTS )    !  Y point coordinates
        INTEGER         NU( 4,NPTS )    !  single-indexed subscripts into grid
        REAL            CU( 4,NPTS )    !  coefficients

    SUBROUTINE UNGRIDI( NCOLS, NROWS, XORIG, YORIG, XCELL, YCELL,
   &                   NPTS, XLOC, YLOC, NX )
        INTEGER         NCOLS, NROWS    !  number of grid columns, rows
        REAL*8          XORIG, YORIG    !  X,Y coords of LL grid corner
        REAL*8          XCELL, YCELL    !  X,Y direction cell size
        INTEGER         NPTS            !  number of (point-source) locations
        REAL            XLOC( NPTS )    !  X point coordinates
        REAL            YLOC( NPTS )    !  Y point coordinates
        INTEGER           NX( NPTS )    !  single-indexed subscripts into grid

C version: none

Summary:

UNGRIDB() computes "ungridding" matrices used by subroutine BMATVEC to perform bilinear interpolation from a grid to a set of target (e.g., point source) locations

{ <XLOC(S),YLOC(S)>, S=1, ..., NPTS }

More detail on the computation of these coefficients, etc., is given in the section on BMATVEC().

UNGRIDI() computes "incidence matrix ungridding" indices for grid-to-grid transformation from a grid to the set of target (e.g., point source) locations as specified above, i.e., so that for a variable V(NCOLS*NROWS) single-indexed on the source grid,

VNEW(S) = V(NX(S)) is the value at { <XLOC(S),YLOC(S)>

Fortran Usage:

For Fortran-90 declarations and interface checking:

    USE M3UTILIO

!! under construction !! (see BMATVEC)

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