Scilab provides about 1.700 mathematical functions for usual engineering and science applications including mathematical operations and data analysis:

• Elementary mathematical functions
  Online Help chapter
• Linear algebra 
  Online Help chapter
• Sparse matrices 
  Online Help chapter on Sparse Matrix 
  Online Help chapter on UMFPACK Interface
• Polynomials and rational functions
  Online Help chapter
• Simulation: explicit and implicit systems of differential equations solvers
  Online Help chapter

See also:

Datasheet - Computation in Scilab

Tutorial - Introduction to Scilab

Available external modules:

• Numerical Maths
• Linear Algebra
• Number Theory