gams:model_a_band_matrix

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gams:model_a_band_matrix [2008/09/25 14:56] support |
gams:model_a_band_matrix [2020/05/18 17:33] (current) Lutz Westermann |
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- | A [[http://en.wikipedia.org/wiki/Band_matrix|band matrix]] can be modeled efficiently in GAMS using circular leads (''++'') and circular lags (''%%--%%''). See chapter 13.4 of the GAMS User's Guide for more information. Using circular leads and lags, the first and last members of the set are assumed to be adjacent, so as to form a circular sequence of members. These operators only work with ordered sets. | + | A [[http://en.wikipedia.org/wiki/Band_matrix|band matrix]] can be modeled efficiently in GAMS using circular leads (''++'') and circular lags (''%%--%%''), see chapter [[https://www.gams.com/latest/docs/UG_OrderedSets.html#UG_OrderedSets_LagLeadOperators|lag and lead operator]] of the GAMS User's Guide for more information. Using circular leads and lags, the first and last members of the set are assumed to be adjacent, so as to form a circular sequence of members. These operators only work with ordered sets. |

- | Find below an example, where the usage of circular leads (equation ''eq'') was ~60 times faster than the original formulation using ''sum'' - statements and lots of comparisons (equation ''eq1'' and ''eq2''). Both models are identical. | + | Find below an example, where the generation of a model with the usage of circular leads (equation ''eq'') was ~50 times faster than the original formulation using ''sum'' - statements and lots of comparisons (equation ''eq1'' and ''eq2''). Both models are identical. |

<code> | <code> |

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