MathML examples in HTML5

Formula A:

\sum_{i = 1}^{p} \sum_{j = 1}^{q} \sum_{k = 1}^{r} a_{i j} b_{j k} c_{k i}

Formula B:

f (x) = {\begin{matrix} 1 / 3 & if 0 \leq x \leq 1; \\ 2 / 3 & if 3 \leq x \leq 4; \\ 0 & elsewhere. \end{matrix}

Formula C:

det | \begin{matrix} c_{0} & c_{1} & c_{2} & \dots & c_{n} \\ c_{1} & c_{2} & c_{3} & \dots & c_{n + 1} \\ c_{2} & c_{3} & c_{4} & \dots & c_{n + 2} \\ ⋮ & ⋮ & ⋮ & ⋮ \\ c_{n} & c_{n + 1} & c_{n + 2} & \dots & c_{2 n} \end{matrix} | > 0