Accuracy of the estimated parameters (panel (a)) and required number of iterations (panel (b)) at different convergence criteria. The discrepancy Δp/p decreases with the criteria ﹩| {\rm{\nabla }}{\mathcal{J}}| /| {\rm{\nabla }}{{\mathcal{J}}}_{0}| ﹩ (the line of slope 1 is shown for reference). On panel (b), note the region of quadratic convergence as the criterion drops below 10⁻³.