Maxima Function
ratvars (x_1, ..., x_n)
ratvars()
ratvarsDeclares main variables x_1, ..., x_n for rational expressions. x_n, if present in a rational expression, is considered the main variable. Otherwise, x_[n-1] is considered the main variable if present, and so on through the preceding variables to x_1, which is considered the main variable only if none of the succeeding variables are present.
If a variable in a rational expression is not present in the ratvars list,
it is given a lower priority than x_1.
The arguments to ratvars can be either variables or non-rational functions
such as sin(x).
The variable ratvars is a list of the arguments of
the function ratvars when it was called most recently.
Each call to the function ratvars resets the list.
ratvars () clears the list.