Non-linear Sparse Constraint Jacobians

[jylambert]

Description

The documentation regarding the constraint Jacobians mentions, "However, we have currently assumed that each of the blocks with an X in is a dense sub-block. pyOptSparse allows each of the sub-blocks to itself be sparse."

If I am passing a constraint Jacobian to a non-linear constraint as a simplified pyOptSparse sparse matrix format, the following error is shown, "pyOptSparse Error: The number of nonzero elements for constraint group 'constraint_1' with respect to var_1 was not the correct size. The supplied Jacobian has 1450 nonzero entries, but must contain 526350 nonzero entries." However, the number of nonzero elements in the Jacobian is 1450; the other entries are 0. The shape (725, 726) of the Jacobian is correct. Does the constraint Jacobians to a non-linear sub-block always have to be dense, or can it also be sparse?