Given a function $g(x,y,z)$ we need to maximize it given constraints $a<x<b, a<y<b$.
If the constraints were given as a function $f(x,y,z)$ the following equation could be used.
$\nabla f(x,y,z) = \lambda \nabla g(x,y,z)$
How would I set up the initial equation given an interval constraint. Or how would I turn the interval constraint into a function constraint.
EDIT:: Added $a<y<b$ to the constraints.