Linear algebra is without a doubt a fundamental tool to deal with empirical economic problems. The goal of this paper is to use some of these techniques to treat business cycles. To do that, we present the classic ordinary least square approach to estime the coefficients of a detrended time...

1. Introduction to R -- 2. Linear Algebra -- 3. Functions of one variable -- 4. Dierential Calculus -- 5. Integral Calculus -- 6. Multivariable Calculus -- 7. Constrained Optimization -- 8. Trigonometry -- 9. Complex numbers -- 10. Difference equations -- 11. Differential equations.