### Derivatives of the defining system of the curve

In the defining system of the object that is to be continued, the derivates can be provided that are needed for the continuation algorithm or other computations. The continuer stores the handle to the derivatives in the variables `cds.curve_jacobian`,`cds.curve_hessians`.

If `cds.symjac`, then a call to `feval(cds.curve_jacobian, x)` must return the Jacobian matrix evaluated at point .

If `cds.symhess`, then a call to `feval(cds.curve_hessians, x)` must return a 3-dimensional ( ) matrix such that .

In the present implementation in most cases `cds.symhess`, so the ODE-file does not provide second order derivatives, since they are not needed in the algorithms used.