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| author | Elizabeth Alexander Hunt <me@liz.coffee> | 2026-07-02 11:55:17 -0700 |
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| committer | Elizabeth Alexander Hunt <me@liz.coffee> | 2026-07-02 11:55:17 -0700 |
| commit | 6bf4b90c90f15f4ab60833bddf5b5756d1a6b1f6 (patch) | |
| tree | ed97e39ec77c5231ffd2c394493e68d00ddac5a4 /Homework/math4610/homeworks/hw-7.org | |
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diff --git a/Homework/math4610/homeworks/hw-7.org b/Homework/math4610/homeworks/hw-7.org new file mode 100644 index 0000000..2c28af2 --- /dev/null +++ b/Homework/math4610/homeworks/hw-7.org @@ -0,0 +1,76 @@ +#+TITLE: Homework 7 +#+AUTHOR: Elizabeth Hunt +#+LATEX_HEADER: \notindent \notag \usepackage{amsmath} \usepackage[a4paper,margin=1in,portrait]{geometry} +#+LATEX: \setlength\parindent{0pt} +#+OPTIONS: toc:nil + +* Question One +See ~UTEST(eigen, dominant_eigenvalue)~ in ~test/eigen.t.c~ and the entry +~Eigen-Adjacent -> dominant_eigenvalue~ in the LIZFCM API documentation. +* Question Two +See ~UTEST(eigen, leslie_matrix_dominant_eigenvalue)~ in ~test/eigen.t.c~ +and the entry ~Eigen-Adjacent -> leslie_matrix~ in the LIZFCM API +documentation. +* Question Three +See ~UTEST(eigen, least_dominant_eigenvalue)~ in ~test/eigen.t.c~ which +finds the least dominant eigenvalue on the matrix: + +\begin{bmatrix} +2 & 2 & 4 \\ +1 & 4 & 7 \\ +0 & 2 & 6 +\end{bmatrix} + +which has eigenvalues: $5 + \sqrt{17}, 2, 5 - \sqrt{17}$ and should thus produce $5 - \sqrt{17}$. + +See also the entry ~Eigen-Adjacent -> least_dominant_eigenvalue~ in the LIZFCM API +documentation. +* Question Four +See ~UTEST(eigen, shifted_eigenvalue)~ in ~test/eigen.t.c~ which +finds the least dominant eigenvalue on the matrix: + +\begin{bmatrix} +2 & 2 & 4 \\ +1 & 4 & 7 \\ +0 & 2 & 6 +\end{bmatrix} + +which has eigenvalues: $5 + \sqrt{17}, 2, 5 - \sqrt{17}$ and should thus produce $2.0$. + +With the initial guess: $[0.5, 1.0, 0.75]$. + +See also the entry ~Eigen-Adjacent -> shift_inverse_power_eigenvalue~ in the LIZFCM API +documentation. +* Question Five +See ~UTEST(eigen, partition_find_eigenvalues)~ in ~test/eigen.t.c~ which +finds the eigenvalues in a partition of 10 on the matrix: + +\begin{bmatrix} +2 & 2 & 4 \\ +1 & 4 & 7 \\ +0 & 2 & 6 +\end{bmatrix} + +which has eigenvalues: $5 + \sqrt{17}, 2, 5 - \sqrt{17}$, and should produce all three from +the partitions when given the guesses $[0.5, 1.0, 0.75]$ from the questions above. + +See also the entry ~Eigen-Adjacent -> partition_find_eigenvalues~ in the LIZFCM API +documentation. + +* Question Six +Consider we have the results of two methods developed in this homework: ~least_dominant_eigenvalue~, and ~dominant_eigenvalue~ +into ~lambda_0~, ~lambda_n~, respectively. Also assume that we have the method implemented as we've introduced, +~shift_inverse_power_eigenvalue~. + +Then, we begin at the midpoint of ~lambda_0~ and ~lambda_n~, and compute the +~new_lambda = shift_inverse_power_eigenvalue~ +with a shift at the midpoint, and some given initial guess. + +1. If the result is equal (or within some tolerance) to ~lambda_n~ then the closest eigenvalue to the midpoint + is still the dominant eigenvalue, and thus the next most dominant will be on the left. Set ~lambda_n~ + to the midpoint and reiterate. +2. If the result is greater or equal to ~lambda_0~ we know an eigenvalue of greater or equal magnitude + exists on the right. So, we set ~lambda_0~ to this eigenvalue associated with the midpoint, and + re-iterate. +3. Continue re-iterating until we hit some given maximum number of iterations. Finally we will return + ~new_lambda~. |
