Fig. 3:

Nonlinear least-squares cost functions associated to deterministic SNL problems often have non-optimal local minima. The graph depicts the landscape of the nonlinear least squares cost function $L(\theta )={\min }_{\tilde{c}\in \mathbb{R}}{\parallel \overrightarrow{\phi }({\theta }_1)-\tilde{c}\overrightarrow{\phi }(\theta )\parallel }_2^2$ associated to a deconvolution problem, where the data is generated by convolving a Ricker wavelet [3] with a single spike located θ₁. In addition to the global minimum at θ₁ there are several spurious local minima.