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## Comments

2 comments

• Gurobi Staff

Hi, Sam!

We created a support ticket to investigate further. Thanks for bringing this to our attention.

• Gurobi Staff

Dear Sam,

The unexpected behavior you observed is the result of disabling presolve without providing a reasonable bound to x (in your example 0<=x<=+inf). Gurobi outputs good approximations for ln(x) when the upper bound of x is set to, for example, 1000.

In any case, it's usually a good idea to keep the presolve on when having PWL approximators such as model.addGenConstrLog(), as it can strengthen bounds.

I hope this information helps.

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