.. _U2.01.02:

**u2.01.02** Instructions for the use of boundary conditions treated by elimination
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**Summary**

The treatment of boundary conditions of the Dirichlet type by elimination (AFFE_CHAR_CINE) does not offer the same generality as by dualization (AFFE_CHAR_MECA for example).

This treatment is to be used when one seeks to improve the execution times of a calculation or if one wishes to work with positive definite matrices.

Note that the boundary conditions available in AFFE_CHAR_ *(* = MECA/THER/ACOU) cannot all be eliminated and treated by AFFE_CHAR_CINE.

This document shows how to use "kinematic loads" in Aster command sets.

There are 3 scenarios (from the simplest to the most complicated):


* We use a "global" calculation command (THER_LINEAIRE, STAT_NON_LINE,...). In this case, kinematic loads are used like other loads.


* We want to do a natural mode calculation. You must then add an argument to the ASSE_MATRICE command.


* We want to do a "step-by-step" calculation and solve linear systems with commands FACTORISER and RESOUDRE. In this case, you must use the CALC_CHAR_CINE command.


.. toctree::
    :hidden:

    self

.. toctree::
    :maxdepth: 2
    :numbered:

    Principe_de_l__limination
    Traitement_dans_Aster
    Exemples_de_fichiers_de_commandes