\def\rload{R_{\rm load}} \def\opt#1{\vskip0pt plus #1\vskip 0pt plus -#1} \input ../format \titlesub{Part 3: Executive Summary}{Mystery Circuit} \input ../com \section{Matrix Representation} To determine the relevant properties of the linear system, matrix form is useful (this form was chosen to reduce fractions' usage): \def\x{{\bf x}} $$\x' = {1\over R_1C_1C_2\rload}\left( \pmatrix{0&-C_2\rload &0 \cr 0&-C_2(R_1+\rload)&-C_1\rload\cr 0&C_2R_1 &-C_1\rload} \x + \pmatrix{\omega\cos(\omega t)\cr \omega\cos(\omega t)\cr 0} \right). $$ The characteristic polynomial is $$-\lambda( (-\lambda-C_2(R_1+\rload))(-\lambda-C_1\rload) + C_2^2R_1\rload).$$ Expanded, $$-\lambda( \lambda^2 + \lambda(C_2(R_1+\rload)+C_1\rload) + C_1C_2\rload(R_1+\rload) + C_2^2R_1\rload).$$ In terms of its roots, $$???$$ \def\bu{\par\leavevmode\llap{\hbox to \parindent{\hfil $\bullet$ \hfil}}} \opt{.15fil} \noindent The eigenvalues and respective eigenvectors are: \bu $\lambda_1 = 0, v_1 = \pmatrix{1\cr0\cr0}$ \def\num{\pmatrix{C_2\rload\cr C_2\rload\cr C_2R_1}} \bu $\lambda_2 = -C_2\rload, v_2 = \num$ \bu $\lambda_3 = -C_2\rload, v_2 = \pmatrix{0\cr0\cr1}$ This gives the solution to the homogenous system $$D_1\pmatrix{1\cr0\cr0} + D_2e^{-C_2\rload t}\num + D_3te^{-C_2\rload t}\pmatrix{0\cr0\cr1}.$$ Extending to the nonhomogenous system, \bye