On grammatical class:

pi'a
n-ary mathematical operator: operands are vectors to be treated as matrix rows.
re'a
unary mathematical operator: matrix transpose/dual; A*.
ri'o
trinary mathematical operator: [integral of a with respect to b over range c].
sa'i
n-ary mathematical operator: operands are vectors to be treated as matrix columns.
sa'o
trinary mathematical operator: [derivative of a with respect to b of degree c].
si'i
trinary mathematical operator: [sigma summation of a using variable b over range c].