# Modeling

Tips and tricks to build optimization models

- NumPy data type in constraint produces error "Constraint has no bool value"
- How do I model a piecewise-linear function of more than one variable?
- Constraint has no bool value (are you trying "lb <= expr <= ub"?)
- How do I multiply an array and a 2-D MVar object using the matrix-friendly Python API?
- How do I pointwise multiply two MVars with the matrix-friendly Python API?
- How do I pointwise multiply a numpy vector with a (1,) MVar with the matrix-friendly Python API?
- How do I multiply two MLinExpr objects together with the matrix-friendly Python API?
- What is the model fingerprint in 9.0 log files?
- How do I export a model from Gurobi?
- Upload Files for Testing, Tuning, and Benchmarking
- Managing Infeasibility
- Where can I learn more about building optimization models?
- How do I model piecewise-linear functions?
- How do I model logical expressions?
- Can I add locally valid constraints in Gurobi MIP?
- How do I manage multiple models in a program?
- Why does an MPS file produce a completely different objective with different solvers?
- What are the differences between LP and MPS file format?
- Why is Gurobi slow to build a model matrix?
- Why do I get random errors when solving the same model on the same computer?
- Why is Gurobi unable to read an LP model file that another solver can successfully read?
- How can Gurobi Optimizer use a model file from lp_solve?
- Model types that Gurobi can solve