If all constraint gradients (Jacobian elements)
are know (Derivative level = 2 or 3), any constant
elements may be given to snopt in the array a
if desired.
The Jacobian array gCon are initialized from the appropriate
elements of a. If any are constant and have the
correct value, funcon need not reassign them in gCon.
Note that constant nonzero elements do affect fCon. Thus, if Jij is assigned correctly in a(*) and is constant, a linear term gCon(i, j)*x(j) or gCon(l)*x(j) must be added to fCon(i) (depending on whether gCon is a two- or one-dimensional array).
Remember, if Derivative level < 2, unassigned elements of gCon are not treated as constant—they are estimated by finite differences at significant expense.