diff --git a/notes/eigen.md b/notes/eigen.md index 34d12e8..a7a9c16 100644 --- a/notes/eigen.md +++ b/notes/eigen.md @@ -91,7 +91,7 @@ $$ |\lambda_1| \geq |\lambda_2| \geq \cdots \geq |\lambda_n|, $$ and we normalize eigenvectors, so that $$\|{\bf x}\| = 1$$. -We define the nullspace as the span, or set of all linear combinations, of the solutions for $$\mathbf {Ax}= \mathbf{b}$$. +We define the nullspace of $$A$$ as the span, or set of all linear combinations, of the solutions for $$\mathbf {Ax}= \mathbf{0}$$. #### Example: Solving a Small Matrix for Eigenvalues @@ -209,7 +209,7 @@ this implies $$ \lim_{k\to\infty}\frac{\mathbf{A}^k {\bf x}_0}{\lambda_1^{k}} = \alpha_1 {\bf u}_1.$$ -This observation motivates the algorithm known as **_power iteration_**, which is the topic of the next section. +Plainly, as we repeatedly apply $$\mathbf{A}$$ to an arbitrary vector - which can always be composed as a linear combination of $$n$$ linearly independent eigenvectors spanning $$\mathbb{R}^n$$ - the result converges to a multiple of the dominant eigenvector of $$\mathbf{A}$$: $$\bf{u_1}$$. This observation motivates the algorithm known as **_power iteration_**, which is the topic of the next section. ## Power Iteration algorithm