Canqi Yao

1. Community
2. Modeling
3. Too much time wasted in adding quadratic constraint for a quadratic minimization problem

Solved! Repalcing large-sized matrix with its sparse matrix can reduce the modeling time!!!

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• Canqi Yao
• May 04, 2024 02:55
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1. Community
2. Programming
3. Error occurred while defining a callback function in class

Hi Eli, Thank you very much, it seems that I have fixed this issue. Best, Canqi  

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• Canqi Yao
• June 29, 2021 02:03
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1. Community
2. Programming
3. Error occurred while defining a callback function in class

Hi Eli, I have revised my code according to what you said, however, there is a new error occurred.   NameError: name 'EPI' is not defined My code is uploaded as the attached file. # Import Gurobi L...

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• Canqi Yao
• June 29, 2021 00:40
• 0 votes

1. Community
2. Algorithms
3. Is there any method to reduce cpu time in callback function ?

Hi Jaromił Apart from reducing time in callback function, can we decrease the number of calling callback function by choosing some nodes with callback function added?  Best Canqi

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• Canqi Yao
• March 03, 2021 13:32
• 0 votes

1. Community
2. Modeling
3. Is there any api which can be used to retrieve the standard form of a linear program in python.

Hi Matthias  Note that when i=0, j=0, and k=0, this constraint = 0 >= -t[0]+ T[0,0] + g[0] * r[0,0] + t[0] - M * (1 - x[0,0,0] which can be further simplified for T[0,0]=0 -g[0]*r[0,0]>= - M * (1 -...

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• Canqi Yao
• January 21, 2021 15:16
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1. Community
2. Modeling
3. Is there any api which can be used to retrieve the standard form of a linear program in python.

As shown in the following figure, the 1st element of bineq should be 5000 in this case ( T[i,i]==0 for i in range(N) ). However, running the code gives me a wrong RHS value.     # branch and cut us...

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• Canqi Yao
• January 21, 2021 14:21
• 0 votes

1. Community
2. Modeling
3. Is there any api which can be used to retrieve the standard form of a linear program in python.

Hi Matthias  Using your recommended code cannot obtain the correct right hand side value for inequality constraints, which has been verified by hand. Can you explain the mechanism of adding constra...

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• Canqi Yao
• January 21, 2021 14:03
• 0 votes

1. Community
2. Modeling
3. Is there any api which can be used to retrieve the standard form of a linear program in python.

Hi Matthias  There is still a problem, can I retrieve A & Aineq respectively. Best Canqi

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• Canqi Yao
• January 21, 2021 01:27
• 0 votes