Free on-line NA-books
- Germund Dahlquist and Åke Björck - Numerical Methods in Scientific Computing
- Lloyd N. Trefethen - Finite Difference and Spectral Methods for Ordinary and Partial Differential Equations
- R. Barrett et. al. - Templates for the Solution of Linear Systems
- Z. Bai et. al. - Templates for the Solution of Algebraic Eigenvalue Problem
- Pravin Varaiya - Lecture Notes on Optimization
- Google Books. Here you can find book previews and look inside chapters of each book for free.