Simplemax uses open source solvers. Descriptions and links to documentation and source code follow.

BFGS Quasi-Newton - source - documentation quasi-Newton method of Broyden, Fletcher, Goldfarb, and Shanno (BFGS). Optimize the function, f, whose gradient is given by fprime using the quasi-Newton method of Broyden, Fletcher, Goldfarb, and Shanno (BFGS) See Wright, and Nocedal 'Numerical Optimization', 1999, pg. 198. COBYLA - source - documentation Constrained Optimization BY Linear Approximation (COBYLA) method. "A direct search optimization method that models the objective and constraint functions by linear interpolation", in Advances in optimization and numerical analysis, Proceedings of the Sixth workshop on Optimization and Numerical Analysis, Oaxaca, Mexico, volume 275 of Mathematics and its Applications, pp 51--67. Kluwer Academic Publishers, 1994. Conjugate Gradient - source - documentation Nonlinear Conjugate Gradient Algorithm. Optimize the function, f, whose gradient is given by fprime using the nonlinear conjugate gradient algorithm of Polak and Ribiere See Wright, and Nocedal 'Numerical Optimization', 1999, pg. 120-122. Galileo - source - documentation Galileo is a global solver, and requires upper and lower bounds. It does not use an initial point and cannot handle Ax <= b constraints. This Genetic Algorithm-based solver was written by Donald Goodman. Modified Powell's method - source - documentation Powell's method, in any number of dimensions. Powell's Method begins with N directions, using a line minimization method. At each iteration the direction in which the function made its largest decrease is discarded. xtol -- acceptable relative error in xopt for convergence. ftol -- acceptable relative error in func(xopt) for convergence. Powell, M. J. D., "An Efficient Method for Finding the Minimum of a Function of Several Variables without Calculating Derivatives," The Computer Journal, 1964, Vol. 7, p. 155 Ralg - source - documentation R-algorithm with adaptive space dilation. "Shor's r-algorithm is an iterative method for unconstrained optimization, designed for minimizing nonsmooth functions, for which its reported success has been considerable." Burke, J.V. et al., "The Speed of Shor's R-Algorithm", Submitted to IMA J. Numer. Anal., 2007 (http://www.optimization-online.org/DB_HTML/2007/05/1656.html) Nelder-Mead Simplex - source - documentation Downhill Simplex method, in any number of dimensions. A simplex in n-dimensions consists of n+1 distinct vertices. The method involves moving a simplex downhill, or if that is not possible, shrinking its size. The method is not highly efficient, and is appropriate only for small numbers of variables (usually fewer than 6), but is robust. xtol -- acceptable relative error in xopt for convergence. ftol -- acceptable relative error in func(xopt) for convergence. J.A. Nelder and R. Mead, The Computer Journal, 1965, Vol. 7, pp 308-313