function [ area, indx, nel, node, nunk, xc ] = geometry ( nnodes, nx )
%
%  [ area, indx, nel, node, nunk, xc ] = geometry ( nnodes, nx )
%
%  GEOMETRY sets up the geometric quantities for the finite element problem.
%
%  NNODES is the number of nodes per element;
%  NX is the number of nodes total.
%
%  AREA(NEL) is the "area" (length, really) of each element.
%  INDX(NX) is the index of the finite element coefficient associated with each node.
%  NEL is the number of elements.
%  NODE(NEL,NNODES) contains a list of the nodes that belong to each element.
%  NUNK is the number of finite element coefficients.
%  XC(NX) is the coordinates of the nodes.
%
  xc = zeros(nx,1);
%
%  The following code produces NX equally spaced nodes from XL to XR.
%
  xl = 0.0;
  xr = 1.0;

  for i = 1 : nx
    xc(i) = ( ( nx - i ) * xl + ( i - 1 ) * xr ) / ( nx - 1 ); 
  end
%
%  Set the values of NODE, which indicate which nodes belong to each element.
%
  nel = nx - 1;
  node = zeros(nel,nnodes);

  for i = 1 : nel
    node(i,1) = i;
    node(i,2) = i+1; 
  end
%
%  Set INDX, which links a node index to a coefficient index.
%
%  In this case, INDX has a very simple form.  In other cases,
%  some values of INDX might be zero.
%
  indx = zeros(nx,1);
  nunk = 0;

  for i = 1 : nx
    nunk = nunk + 1;
    indx(i) = nunk;
  end 
%
%  Set AREA, the area of each element.
%
  area = zeros(nel,1);

  for it = 1 : nel
    ip1 = node(it,1);
    ip2 = node(it,2); 
    x1 = xc(ip1);
    x2 = xc(ip2); 
    area(it) = abs ( x2 - x1 );
  end