Hi, I finally committed the scipy.optimize.nonlin rewrite that was pending for a long time. What is now there for large-scale root finding is: * Newton-Krylov method (``scipy.optimize.newton_krylov``) * Generalized secant methods: - Limited-memory Broyden (``scipy.optimize.broyden1``, ``scipy.optimize.broyden2``) - Anderson (``scipy.optimize.anderson``) * Simple iterations (``scipy.optimize.diagbroyden``, ``scipy.optimize.excitingmixing``, ``scipy.optimize.linearmixing``) Here's a simple demo: http://docs.scipy.org/doc/scipy/reference/tutorial/optimize.html#large-probl... -- Pauli Virtanen