rf.spad line 153 [edit on github]
Utilities that provide the same top-level manipulations on fractions than on polynomials.
coerce(r) returns r viewed as a rational function over R.
eval(f, v = g) returns f with v replaced by g. Error: if v is not a symbol.
eval(f, [v1 = g1, ..., vn = gn]) returns f with each vi replaced by gi in parallel, i.e. vi's appearing inside the gi's are not replaced. Error: if any vi is not a symbol.
eval(f, [v1, ..., vn], [g1, ..., gn]) returns f with each vi replaced by gi in parallel, i.e. vi's appearing inside the gi's are not replaced.
eval(f, v, g) returns f with v replaced by g.
mainVariable(f) returns the highest variable appearing in the numerator or the denominator of f, "failed" if f has no variables.
multivariate(f, v) applies both the numerator and denominator of f to v.
univariate(f, v) returns f viewed as a univariate rational function in v.
variables(f) returns the list of variables appearing in the numerator or the denominator of f.