eturn:
%
% * function values of all constraints (*nonlinear followed by linear*) as a
%   vector |g| of dimensions |(NgNLN+NgLIN) x 1|,
% * gradients of all constraints as a (possibly sparse) matrix |dg| of 
%   dimensions |(Nx+NYnnz) x (NgNLN+NgLIN)|,
% * hessian of the |k|-th nonlinear (function) constraint (|k=1..NgNLN|)
%   as a (possibly sparse) matrix |ddgk| of dimensions 
%   |(Nx+NYnnz) x (Nx+NYnnz)|; if |NgNLN = 0|, |conhess()| needn't be defined.
%
% Alternatively, it is possible to spec