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%XREGARX/ABOUT_CODING Help on how coding is implemented for XREGARX models % All models operate in two modes: fitting (training) and evaluation % (simulation). % % Fitting: % +------------+ % inputs (x) --->| XREGMODEL/ |---> model (m) % outputs (y) -->| FITMODEL | % +------------+ % Evaluation: % +------------+ % inputs (x) --->| XREGMODEL/ |---> predictions (yhat) % model (m) ---->| EVALMODEL | % +------------+ % % If there is no feedback inside the XREGARX model, then coding is trival: it % only effects the genuine inputs and is all handled by the XREGMODEL % inherited by the XREGARX model. % % In the case that there is feedback, things get a little more complicated. % The XREGMODEL inherited by the XREGARX model handles the coding of the % genuine inputs but the embedded static model needs to be told the ranges of % of the feedback inputs. This is done in XREGARX/RUNFIT. The input to the % static model fitting method, i.e., FITMODEL, is the genuine model inputs in % coded units and the feedback outputs in natural units. FITMODEL will then % encode this data: the genuine inputs will be unaffected as the static model % will have [-1,1] as the range of those terms and the feedback outputs will % be correctly coded. % % During fitting the model must evaluate itself and use these predictions as % inputs at subsequent timesteps. Because these feedback inputs must be in % coded units, the outputs (y) to the static model fitting process get coded % first. Thus the predictions made by the static model are in coded units and % suitable to be feed back in as inputs. It also means that in evaluation % mode that output of the static model must be uncoded before output from the % XREGARX model. This uncoding is done in XREGARX/EVAL. % % See also XREGMODEL, XREGMODEL/FITMODEL, XREGARX, XREGARX/RUNFIT, % XREGARX/EVAL % % Routines for handling coding % XREGMODEL/CODE Perform input (x) coding % XREGMODEL/INVCODE Invert input (x) coding % XREGMODEL/SETCODE % XREGMODEL/GETCODE % Copyright 2000-2004 The MathWorks, Inc. and Ford Global Technologies, Inc. %------------------------------------------------------------------------------| % EOF %------------------------------------------------------------------------------|