C     function d = find_min_dist(lx,ly,x,y)
C
C     Given a grid (x,y) and a line (lx,ly) compute the minimum distance
C     from each point of (x,y) to a point on the line.
C
C     Written by George Beckett - Matlab 5.3 MEX,
C     Friday 9th March 2001.
C
      SUBROUTINE mexFunction(nlhs, plhs, nrhs, prhs)
      INTEGER plhs(*), prhs(*)
      INTEGER nlhs, nrhs
      INTEGER m, n, n2
      INTEGER plx, ply, px, py, pd
C
C     Firstly, validate input and output arguments.
C
      IF (nrhs .NE. 4) THEN
         CALL mexErrMsgTxt('Invalid no. input arguments.')
      ELSE IF (nlhs .NE. 1) THEN
         CALL mexErrMsgTxt('Invalid no. input arguments.')
      ENDIF
C
C     Then read input arguments.
C
      plx = mxGetPr(prhs(1))
      ply = mxGetPr(prhs(2))
      px = mxGetPr(prhs(3))
      py = mxGetPr(prhs(4))
C
C     Get size of grid matrices and length of line vector.
C
      m = mxGetM(prhs(3))
      n = mxGetN(prhs(3))
      n2 = mxGetN(prhs(1))
C
C     Allocate space for the minimum distance matrix
C
      plhs(1) = mxCreateFull(m,n,0)
      pd = mxGetPr(plhs(1))
C
C     Step through the mesh one point at a time
C
      CALL compmind(%val(px), %val(py), %val(pd),
     &     %val(plx), %val(ply), m, n, n2)
C
      RETURN
C
      END
C     
C     This is the subroutine which computes the minimum distance
C     
      SUBROUTINE compmind(xmtx, ymtx, distmtx, lx, ly, m, n, n2)
C
      PARAMETER (LDOMAIN = 100.0)
C
      INTEGER m, n, n2
      INTEGER ii, jj, kk
      REAL*8 xmtx(m,n), ymtx(m,n), distmtx(m,n)
      REAL*8 lx(n2), ly(n2)
      REAL*8 dist, mindist
C
      DO 30 jj=1,n
         DO 20 ii=1,m
            mindist = LDOMAIN
C
            DO 10 kk=1,n2
               dist=(lx(kk)-xmtx(ii,jj))**2+(ly(kk)-ymtx(ii,jj))**2
C
               IF(dist .LT. mindist) mindist=dist
 10         CONTINUE
C     
            distmtx(ii,jj)=mindist
 20      CONTINUE
 30   CONTINUE
      
      RETURN
      END