Figure out how to format $M_s$, $M_t$ and $s_m$ [global]

[Richard Murray]

Need to figure out how to handle $M_\text{s}$ and $M_\text{t}$, which are used for the peak sensitivity and complementary sensitivity. Strictly speaking, these should probably be $M_S$ and $M_T$, but we have chosen to use lower case. Should $s$ and $t$ be considered variables in this context? Or does "s" represent the word "sensitivity" (in which case $M_\text{s}$ is appropriate, but $M_\text{t}$ is odd).}

Also: we use $s_m$ for the sensitivity margin. Not clear if the subscript represents an English word (margin) or not.

[Richard Murray]

In the current text, we are using $M_\text{s}$, $M_\text{t}$, and $s_\text{m}$. We also use $g_\text{m}$ for gain margin and $\varphi_\text{m}$ for phase margin.

[Richard Murray]

24 Jul 2019: leave as is.