XSPEC> method anneal [<# of eval> [<crit delta> [<start temp> [<temp reduction factor>]]]]
An experimental global minimization method using a simulated annealing algorithm. This needs tuning to work well for X-ray data. <# of eval> is the number of function evaluations to perform before giving up, <crit delta> is the convergence criterion, <start temp> is the initial annealing temperature, and <temp reduction factor> is the fractional reduction in temperature for each cycle.