.. _U4.67.01:

**u4.67.01** Operator DEFI_BASE_REDUITE
=========================================

The aim of the operator is to build the reduced base from a non-linear calculation (thermal or mechanical) or a parametric linear calculation.

There are two methods:


* For non-linear problems, the operator relies on an sd_result of the evol_ther or evol_noli type and performs a singular value decomposition (SVD) on the transient or an incremental POD strategy;


* For parametric linear problems, a glutton algorithm is used. In this case, we define the linear system to be solved.

The operator also allows you to truncate a base (primal or dual) on a reduced domain (for example produced by the DEFI_DOMAINE_REDUIT command).

Two types of bases can be produced:


* the so-called "primal" bases: they are based on displacement fields for mechanics and on temperature fields for thermal purposes;


* the so-called "dual" bases: they are based on stress fields for mechanics and on flow fields for thermal engineering.

The operator produces a mode_empi concept.




.. toctree::
    :hidden:

    self

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

    Syntaxe
    Op_randes
    Exemples_d_utilisation