Try our new documentation site (beta).


Type: int
Modifiable: Yes

Number of objectives in the model. If you modify this attribute, it will change the number of objectives in the model. Decreasing it will discard existing objectives. Increasing it will create new objectives (initialized to 0). Setting it to 0 will create a model with no objective (i.e., a feasibility model). If you want to switch from a multi-objective model to a single-objective model you also need to set NumObj to 0 and call model update before installing a new single objective.

You can use the ObjNumber parameter, in conjunction with multi-objective attributes (ObjN, ObjNName, etc.), to query or modify attributes for different objectives. The value of ObjNumber should always be less than NumObj.

Please refer to the discussion of Multiple Objectives for more information on the use of alternative objectives.

For examples of how to query or modify attributes, refer to our Attribute Examples.

Try Gurobi for Free

Choose the evaluation license that fits you best, and start working with our Expert Team for technical guidance and support.

Evaluation License
Get a free, full-featured license of the Gurobi Optimizer to experience the performance, support, benchmarking and tuning services we provide as part of our product offering.
Academic License
Gurobi supports the teaching and use of optimization within academic institutions. We offer free, full-featured copies of Gurobi for use in class, and for research.
Cloud Trial

Request free trial hours, so you can see how quickly and easily a model can be solved on the cloud.