pne_pfcn_natural

pne_pfcn_natural(x, xp, step, zp)

pne_pfcn_natural() - Natural parameterization function for PNE.

[P, DP] = PNE_PFCN_NATURAL(X, XP, STEP)
[P, DP] = PNE_PFCN_NATURAL(X, XP, STEP, ZP)

This function defines a "natural" parameterization for a PNE, where the
step size is the difference between current and previous values of the
parameter lambda.

Inputs:
    X    : solution vector x (last element is parameter lambda)
    XP   : previous solution vector
    STEP : continuation parameter step size
    ZP   : normalized tangent vector at XP (not used by this
           parameterization)

Outputs:
    P : value of parameterization function
    DP : Jacobian of paramerization function (transpose of gradient)