hessian_constant:

Indicates whether the problem is a quadratic problem $\;$
Activating this option will cause Ipopt to ask for the Hessian of the Lagrangian function only once from the NLP and reuse this information later. The default value for this string option is "no".
Possible values:

• no: Assume that Hessian changes
• yes: Assume that Hessian is constant