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gams:should_i_use_bounds_or_singleton_equations

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gams:should_i_use_bounds_or_singleton_equations [2007/09/28 13:30]
127.0.0.1 external edit
gams:should_i_use_bounds_or_singleton_equations [2007/10/20 07:44] (current)
Franz Nelissen
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 In general bounds (i.e. ''​x.lo'',​ and ''​x.up''​) are more efficient than equations: a bound does not make the model bigger while an equation does. For solvers with good presolvers this advantage is less pronounced, as the presolver will convert "​singleton equations"​ like x(i) =g= 1000; into bounds automatically. In general bounds (i.e. ''​x.lo'',​ and ''​x.up''​) are more efficient than equations: a bound does not make the model bigger while an equation does. For solvers with good presolvers this advantage is less pronounced, as the presolver will convert "​singleton equations"​ like x(i) =g= 1000; into bounds automatically.
  
-Similarly preferably you should not generate many ''​.fx''​ fixed variables. In many cases you can use dollar conditions in the model so that GAMS will not generate them. You can also use the ''​.holdfixed''​ model suffix; this will cause GAMS to consider fixed variables as constants. Again, for a solver with a good presolver many fixed +Similarly preferably you should not generate many ''​.fx''​ fixed variables. In many cases you can use dollar conditions in the model so that GAMS will not generate them. You can also use the ''​.holdfixed''​ model suffix; this will cause GAMS to consider fixed variables as constants. Again, for a solver with a good presolver many fixed variables are not an issuethey will be removed from the model automatically.
-variables are not an issue:they will be removed from the model automatically.+
  
IMPRESSUM / LEGAL NOTICEPRIVACY POLICY gams/should_i_use_bounds_or_singleton_equations.txt · Last modified: 2007/10/20 07:44 by Franz Nelissen