When you run the program, you will see the main window as in Figure 1.1, “The contour plot”. The menubar has 3 menus.
-> opens a new coordinate file.
-> saves contour plot, mesh, gradient, potentials etc.
-> exits the program.
-> draws the mesh.
-> draws the contours.
-> fills colours according to the contours.
-> draws the gradient.
-> draws the legend.
-> draws the output i.e. contours, gradient. In this mode you can modify triangle properties ( boundary ) and divide triangles into more triangles.
-> draws the input i.e. different materials will have different colours. In this mode, you can modify material properties using the popup menu.
-> You can change drawing preferences such as background colour by selecting this menuitem.
-> regenerates the mesh and solves the problem, using only one iteration.
-> solves the problem without generating the mesh again.
-> generates the mesh, and solves the problem iteratively, until iteration limit has reached. In each iteration, the mesh is refined.
-> integrates the potential to find the charge (in an electrostatic problem) on Dirichlet boundaries.
-> If you enable this mode, you can edit material properties just by clicking on a material. You need to select this menuitem again to disable this mode.
Figure 1.6, “Solve Options Dialog” for more detail.-> dialog window for changing solution options. See
The options that can be changed using the above dialog are as follows:
Min. Area: Minimum area of a triangle of the mesh.
Max. Area: Maximum area of a triangle of the mesh.
Tri. Badness: Maximum badness of a triangle in the mesh. Badness is the ratio of the longest edge to the shortest edge of a triangle.
Poisson for Poisson and Laplace equations.
Poisson (Sparse) for Poisson and Laplace equations using sparse matrices and Conjugate Gradient solver.
Homogeneous Helmholtz for homogeneous waveguide (eigenvalue problems).
Inhomogeneous Helmholtz for inhomogeneous waveguide problems.
Helmholtz find beta for finding the propagation constant when the frequency or k is given.
Helmholtz find k0 for finding the frequency when the propagation constant is given.
Use Full Matrix Solver: Most eigenvalue problems have symmetric positive definite matrices. So, we only need half of the matrix for solution. However, the problems where we have to find beta and k0 will not always give us positive definite matrices. So in this case, enable this option to use full matrices.
Use ARPACK Eigensolver: If you have a very large problem to solve (several thousand unknowns), select this option. It will use very little memory but takes longer time.
No. of Eigenmodes: Only for equation other than Poisson, the number of eigenmodes to find, starting from the dominant mode.
Contour Levels: No. of contour levels to plot
Iteration Limit: Maximum no of iterations in the iterative form of solution.
Wave frequency beta: used when solving Helmholtz find k0 problems.
Wave frequency k0: used when solving Helmholtz find beta problems.
Note that the units used in all of the above parameters are normalised. In other words, you do not have to worry about units or absolute values.
This is the menu you get fromclicking the mouse. It has following items.
-> switch to default mode. Basically does nothing. Useful if you want to stop zooming etc.
Figure 1.7, “Triangle Info Dialog” and you can change the boundary of the triangle.-> Switch to retrieving and changing properties of triangles. In this mode, If you are in -> mode, once you left-click on a triangle, you get a dialog like
If you are in Figure 1.8, “Material Info Dialog” and you can change the boundary properties like permittivity and permeability. This is useful especially if you need to solve inhomogeneous waveguide problems where you need to specify both the permittivity and permeability.-> mode, once you left-click on any area, you get a dialog like
-> In this mode, once you left-click on a triangle, it will be split. This is useful if you need to manually refine the generated mesh.
-> In this mode, you can select a rectangular area using the mouse button and zoom in.
-> Once you select this option, the display will zoom back to previous view.
-> Once you select this option, the display will zoom to global view.
Figure 1.3, “3D contour plot”. In the 3D window, you can zoom and rotate using mouse buttons. Move the mouse with pressed for rotation. Move the mouse with pressed for zooming.-> Once you select this option, a new window will be created to display the contour plot in 3D like
-> This option is useful if you solve the Helmholtz equation for more than one eigenmode. By selecting this option, you can switch between each eigenmode.
-> Exits the program.