Eli Towle

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3. How to use PWL and Multi-Objectives together

Hi Hans, Are any of the piecewise linear functions convex (assuming you're minimizing)? If so, you can instead use a more efficient linear formulation to model the piecewise linear function. This i...

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• Eli Towle
• August 23, 2019 18:04
• 1 vote

1. Community
2. Algorithms
3. Cut loop at root node of MIP

Hi Fan, The MIPNODE callback is called once for each cut pass that occurs at the root node. This is described in more detail in the callback codes documentation. I hope this helps. Thanks! Eli

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• Eli Towle
• August 23, 2019 16:20
• 0 votes

1. Community
2. Programming
3. How to use PWL and Multi-Objectives together

Hi Hans, There is no way to use piecewise linear objectives with setObjectiveN(). However, you can add piecewise linear constraints (see here), and then set the multiple objectives to be the variab...

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• Eli Towle
• August 22, 2019 22:33
• 1 vote

1. Community
2. Programming
3. Need help with Objective function

Hi Suhas, The scipy.optimize.newton method finds a zero of the given function. This is different from what is meant by the optimization problem in your code. As written, the goal of your optimizati...

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• Eli Towle
• August 08, 2019 19:13
• 0 votes

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2. Programming
3. Problem in Understanding the difference between the two approaches (1. accessing a list value directly for comparison in constraint. 2 assigning the list values to a variable and then comparing it in a constraint

Hi Vaibhav, Okay, thanks for the clarification. With (1), there are still variables in the constraint, because the Vpredicted linear expression includes the Rl, Rm, and Rh variables. It seems that ...

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• Eli Towle
• July 30, 2019 01:05
• 0 votes

1. Community
2. Programming
3. Problem in Understanding the difference between the two approaches (1. accessing a list value directly for comparison in constraint. 2 assigning the list values to a variable and then comparing it in a constraint

Hi Vaibhav, First, I'll clarify a few general concepts related to optimization. The line vulvar=m.addVars(len(Vul), vtype=GRB.CONTINUOUS, obj=Vul,name="vul") adds a number of nonnegative continuous...

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• Eli Towle
• July 29, 2019 22:14
• 0 votes

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2. Programming
3. Issue with binary variables

Hi Mirna, For numerical reasons, an integrality constraint on a variable is considered satisfied if the variable value is "close enough" to an integer. By default, this tolerance is 1e-5. You can t...

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• Eli Towle
• July 24, 2019 21:17
• 1 vote

1. Community
2. Programming
3. gurobipy - add specific constraints as "Lazy"

Hi Niccolò, Here is a simple example showing how to set the Lazy attribute after creating the constraints. # addConstrs() returns tupledict of constraintsmyconstrs = m.addConstrs(x[i] + y[i] <= 1 f...

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• Eli Towle
• July 22, 2019 16:04
• 1 vote

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2. Systems
3. How can limit 'Thread count' instead of using 'all available processors'?

Hi Kamal, This can be done as follows: optimizer = SolverFactory('gurobi')optimizer.options['threads'] = 1 For more information about passing options to solvers, see the Pyomo documentation on the ...

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• Eli Towle
• July 16, 2019 21:28
• Edited
• 1 vote

1. Community
2. Algorithms
3. Will Gurobi retain lazy cuts after changing the objective coefficients?

Hi Austin, I'll assume you're asking about "lazy constraints" as opposed to "user cuts." For more information on the difference between these two, see this article. Lazy constraints are required fo...

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• Eli Towle
• June 18, 2019 12:38
• Edited
• 1 vote