The main subroutine of CalculiX is ccx_2.15.c. It consists roughly of the following parts:

- Allocation of the fields

- Reading the step input data (including the prestep data for the first step)
- Determining the matrix structure
- Filling and solving the set of equations, storing the results.

- Allocation of the fields

- Reading the step input data
- SPC's
- Homogeneous linear equations
- Concentrated loads
- Facial distributed loads
- Mechanical body loads
- Sets
- Material description

- Expansion of the one-dimensional and two-dimensional elements
- Cataloguing the elements belonging to a given node
- Calculating the normals in the nodes
- Expanding the 1D and 2D elements
- Connecting 1D and 2D elements to 3D elements
- Applying the SPC's to the expanded structure
- Applying the MPC's to the expanded structure
- Applying temperatures and temperature gradients
- Applying concentrated forces to the expanded structure
- Integrating the stresses in beams to obtain the section forces

- Contact
- Determining the matrix structure

- Filling and solving the set of equations, storing the results
- Linear static analysis
- Nonlinear calculations
- Frequency calculations
- Buckling calculations
- Modal dynamic calculations
- Steady state dynamics calculations

- Major routines

- Aerodynamic and hydraulic networks
- The variables and the equations
- Determining the basic characteristics of the network
- Initializing the unknowns
- Calculating the residual and setting up the equation system
- Convergence criteria

- Three-Dimensional Navier-Stokes Calculations
- Sensitivity Analysis

- Mesh refinement
- Nodal fields
- Edge fields
- Face fields
- Element fields
- Mesh refining procedure
- cattet.f
- catedges.f
- determineextern.f
- midexternaledges.f
- midexternalfaces.f
- START OF MAJOR LOOP
- first loop: calculateh.f
- first loop: getlocalresults.f
- all but the first loop: calculated.f
- START OF THE REFINEMENT OF THE EXTERNAL EDGES
- edgedivide.f
- newnodes.f
- cavityext.f
- START OF THE REFINEMENT OF THE INTERNAL EDGES.
- .
- cavity.f
- END OF MAJOR LOOP.
- .

- List of variables and their meaning

guido dhondt 2018-12-15