Proper generalized decomposition: Difference between revisions

Content deleted Content added
Kokoo (talk | contribs)
mNo edit summary
Kokoo (talk | contribs)
No edit summary
Line 2:
The '''proper generalized decomposition''' ('''PGD''') is an [[iterative method|iterative]] [[numerical method]] for solving [[boundary value problem]]s (BVPs), that is, [[partial differential equation]]s constrained by a set of boundary conditions, such as the [[Poisson's equation]] or the [[Laplace's equation]].
 
The PGD algorithm computes an approximation of the solution of the BVP by successive enrichment. This means that, in each iteration, a new component (or ''mode'') is computed and added to the approximation. In principle, the more modes obtained, the closer the approximation is to its theoretical solution. However, due to theUnlike [[greedyProper algorithmorthogonal decomposition|greedyPOD]] natureprincipal of thecomponents, PGD algorithm,modes someare modesnot maynecessarily actually[[orthogonal]] worsento theeach approachother.
 
By selecting only the most relevant PGD modes, a [[reduced order model]] of the solution is obtained. Because of this, PGD is considered a [[dimensionality reduction]] algorithm.
Line 28:
 
=== Greedy algorithm ===
The solution is sought by applying a [[greedy algorithm]], usually the [[fixed point algorithm]], to the [[weak formulation]] of the problem. For each iteration ''i'' of the algorithm, a ''mode'' of the solution is computed. Each mode consists of a set of numerical values of the functional products '''X<sub>1</sub>'''(''x''<sub>1</sub>), ..., '''X<sub>d</sub>'''(''x''<sub>d</sub>), which ''enrich'' the approximation of the solution. Note that dueDue to the greedy nature of the algorithm, the term 'enrich' is used rather than 'improve', since some modes may actually worsen the approach. The number of computed modes required to obtain an approximation of the solution below a certain error threshold depends on the stop criterium of the iterative algorithm. For the same reason and unlike [[Proper orthogonal decomposition|POD]], PGD modes are not necessarily [[orthogonal]] to each other.
 
== Features ==