Exponentiating $2×2$ and $3×3$ Matrices Done Right

@misc{citeulike:2152626, abstract = {We derive explicit formulas for calculating \$e^A\$, \$\cosh{A}\$, \$\sinh{A}, \cos{A}\$ and \$\sin{A}\$ for a given \$2\times2\$ matrix \$A\$. We also derive explicit formulas for \$e^A\$ for a given \$3\times3\$ matrix \$A\$. These formulas are expressed exclusively in terms of the characteristic roots of \$A\$ and involve neither the eigenvectors of \$A\$, nor the transition matrix associated with a particular canonical basis. We believe that our method has advantages (especially if applied by non-mathematicians or students) over the more conventional methods based on the choice of canonical bases. We support this point with several examples for solving first order linear systems of ordinary differential equations with constant coefficients.}, author = {Popov, Angel P. and Todorov, Todor D. }, citeulike-article-id = {2152626}, eprint = {0712.2632}, keywords = {linear-algebra, matrix, teaching}, month = {Dec}, posted-at = {2007-12-20 18:16:04}, priority = {2}, title = {Exponentiating \$2\times2\$ and \$3\times3\$ Matrices Done Right}, url = {http://arxiv.org/abs/0712.2632}, year = {2007} }

TY - ELEC ID - citeulike:2152626 L3 - citeulike-article-id:2152626 TI - Exponentiating $2\times2$ and $3\times3$ Matrices Done Right N2 - We derive explicit formulas for calculating $e^A$, $\cosh{A}$, $\sinh{A}, \cos{A}$ and $\sin{A}$ for a given $2\times2$ matrix $A$. We also derive explicit formulas for $e^A$ for a given $3\times3$ matrix $A$. These formulas are expressed exclusively in terms of the characteristic roots of $A$ and involve neither the eigenvectors of $A$, nor the transition matrix associated with a particular canonical basis. We believe that our method has advantages (especially if applied by non-mathematicians or students) over the more conventional methods based on the choice of canonical bases. We support this point with several examples for solving first order linear systems of ordinary differential equations with constant coefficients. KW - linear-algebra KW - matrix KW - teaching AU - Popov, Angel AU - Todorov, Todor PY - 2007/Dec/17/ UR - http://arxiv.org/abs/0712.2632 ER -