29 April     2007   8:20:06.000 AM      
  
 FEM1D
   FORTRAN77 version.
  
   A finite element solver for a 1D problem.
  
   Solve the two-point boundary value problem
  
   -d/dx ( P(x) dU(x)/dx ) + Q(x) U(x) = F(x)
  
   on the interval [XL,XR], specifying
   the value of U or U' at each end.
  
   The interval [XL,XR] is broken into NSUB =  5 subintervals
   Piecewise linear finite element functions are used.
   The number of basis functions that are nonzero
   in any element is at most NL =  2
  
 The equation is to be solved for
 X greater than XL =   0. and less than XR =   1.
  
 The boundary conditions are:
  
   At X=XL, U=  0.
   At X=XR, U'=  1.
  
 Number of quadrature points per element is  1
  
   Node      Location
  
 0  0.
 1  0.2
 2  0.4
 3  0.6
 4  0.8
 5  1.
  
 Subint    Length
  
 1  0.2
 2  0.2
 3  0.2
 4  0.2
 5  0.2
  
 Subint    Quadrature point
  
 1  0.1
 2  0.3
 3  0.5
 4  0.7
 5  0.9
  
 Subint  Left Node  Right Node
  
 1 0 1
 2 1 2
 3 2 3
 4 3 4
 5 4 5
  
   Number of unknowns NU =  5
  
   Node  Unknown
  
 0 -1
 1 1
 2 2
 3 3
 4 4
 5 5
 
The tridiagonal linear system:
 
Equation  ALEFT  ADIAG  ARITE  RHS
 
 1  0.  10. -5.  0.
 2 -5.  10. -5.  0.
 3 -5.  10. -5.  0.
 4 -5.  10. -5.  0.
 5 -5.  5.  0.  1.
  
 Computed solution:
  
 Node    X(I)        U(X(I))
  
 0  0.  0.
 1  0.2  0.2
 2  0.4  0.4
 3  0.6  0.6
 4  0.8  0.8
 5  1.  1.
  
 FEM1D
   Normal end of execution.
  
29 April     2007   8:20:06.000 AM