Date: 2023-02-12 | Article ID: 18505 |

This article gives a brief review of matrix algebra, introduces the concept of the exponential of a matrix, and derives a useful identity for the derivative of the inverse or determinant of a matrix with respect to one of its components.

**2023-02-12**(removed an incorrect statement from the new footnote)**2023-02-10**(added a footnote about an alternative definition of eigenvalue)**2022-06-11**(updated references to other articles in this series to link to html abstract pages instead of to pdfs. Didn't change the version number/date)**2022-02-20**(in the null-rotation example: clarified one sentence and added an equation)**2022-02-18**(added a null-rotation example, reformatted to avoid a page break)**2022-02-06**(fixed inconsistent notation in derivation of derivative of inverse matrix)**2022-02-05**(first version)

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