For standard and large-scale optimization issues, Scilab provides algorithms to solve constrained and unconstrained continuous and discrete problems:

• Nonlinear optimization
• Quadratic optimization
• Nonlinear least-square optimization
• Semidefinite programming
• Genetic algorithms 
  Online Help chapter
• Simulated annealing
  Online Help chapter
• Linear matrix inequalities

See also:

Datasheet - Optimization in Scilab

Tutorial - Optimization in Scilab (updated 09/2011)

Scilab Functions

Available external modules