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AMPL Frequently Asked Questions
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1
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141
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February 23, 2023
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Why do I get an “invalid subscript discarded” message when I display an AMPL parameter?
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0
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343
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December 15, 2021
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Can I get a version of AMPL that will run on my computer, under my computer’s operating system?
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0
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153
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December 15, 2021
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What is AMPL (A Mathematical Programming Language)?
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0
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147
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December 15, 2021
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How does AMPL compare to spreadsheet optimizers?
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0
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160
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December 15, 2021
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How does AMPL compare to other modeling languages and systems?
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0
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154
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December 15, 2021
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How can I learn more about AMPL?
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0
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121
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December 15, 2021
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How big a problem can AMPL solve?
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0
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146
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December 15, 2021
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Can my program call AMPL as a subroutine?
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0
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126
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December 15, 2021
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How can I edit my model or data file without leaving the AMPL command environment?
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0
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131
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December 15, 2021
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How do I solve a series of different random problems with data drawn from the same distribution?
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0
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133
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December 15, 2021
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When does AMPL evaluate the conditions specified in my model’s check statements?
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0
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139
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December 15, 2021
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How do I write an “MPS file” for my problem?
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0
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275
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December 15, 2021
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Why does AMPL write an MPS file that is different from what I expect?
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0
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132
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December 15, 2021
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What are the transformations that AMPL applies to optimization problems?
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0
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120
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December 15, 2021
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How can I prevent AMPL from transforming my problem?
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0
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128
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December 15, 2021
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Why does AMPL reject my “let” statement with a “… has a := value in the model” message?
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0
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147
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December 15, 2021
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What does AMPL mean by “syntax error”? I double-checked the offending statement in the AMPL book, and my syntax is fine
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0
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234
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December 15, 2021
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How can I tell whether messages on my screen are coming from AMPL or from the solver?
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0
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123
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December 15, 2021
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Why does AMPL appear to “hang” for a long time without accepting any input or producing any output?
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0
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128
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December 15, 2021
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Why does AMPL unexpectedly abort in the middle of doing something? I get a short error message, but I can’t find it explained in the AMPL book or in the solver documentation
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0
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126
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December 15, 2021
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What should I do if I suspect that there is insufficient memory for my AMPL session?
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0
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133
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December 15, 2021
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Why doesn’t AMPL interpret the expression T..1 as I expect?
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0
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115
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December 15, 2021
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Why does “set S := 50 .. 70” give me a set of only 3 members?
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0
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140
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December 15, 2021
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I have declared “set S” and “param b {S}”. How do I write an AMPL expression for the arg min of b[i] — that is, the s in S such that b[s] equals the minimum of b[i] over al
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0
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161
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December 15, 2021
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How can I get AMPL to index over the “power set” consisting of all subsets of a set?
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0
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146
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December 15, 2021
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How can I apply AMPL’s ordered-set functions to pairs and higher-dimensional objects?
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0
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145
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December 15, 2021
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When I set option substout 1, why doesn’t AMPL make the substitutions that I expect?
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0
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113
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December 15, 2021
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Why does AMPL treat my linear program as nonlinear?
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0
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141
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December 15, 2021
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When certain variables are fixed, the nonlinear expressions in my model all become linear. Does AMPL consider my model to be linear in this case?
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0
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118
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December 15, 2021
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