RationalPoly in as_polynomial

Author: shashi

src/polyform.jl

@@ -48,10 +48,27 @@ function as_polynomial(f, exprs...; polyform=false, T=Real)
     @assert length(exprs) >= 1 "At least one expression must be passed to `multivariatepolynomial`."
 
     pvar2sym, sym2term = get_pvar2sym(), get_sym2term()
-    ps = map(x->PolyForm(x, pvar2sym, sym2term), exprs)
-    convert_back = polyform ? x -> PolyForm{T}(x, pvar2sym, sym2term) :
-        x -> unpolyize(PolyForm{T}(x, pvar2sym, sym2term)) # substitute back
-    res = f(convert_back, map(x->x.p, ps)...)
+    ps = map(exprs) do x
+        if istree(x) && operation(x) == (/)
+            num, den = arguments(x)
+            PolyForm(num, pvar2sym, sym2term).p /
+            PolyForm(den, pvar2sym, sym2term).p
+        else
+            PolyForm(x, pvar2sym, sym2term).p
+        end
+    end
+
+    convert_back_f = function (x)
+        if x isa MultivariatePolynomials.RationalPoly
+            PolyForm{T}(numerator(x), pvar2sym, sym2term) /
+            PolyForm{T}(denominator(x), pvar2sym, sym2term)
+        else
+            PolyForm{T}(x, pvar2sym, sym2term)
+        end
+    end
+
+    convert_back = polyform ? convert_back_f : unpolyize ∘ convert_back_f
+    res = f(convert_back, ps...)
 end
 
 # We use the same PVAR2SYM bijection to maintain the PolyVar <-> Sym mapping,

test/polyform.jl

@@ -84,4 +84,9 @@ end
     @eqtest as_polynomial((f, x, y) -> f(gcd(x, y)), 10x+10y, 5*(x^2-y^2)) == 5x + 5y
     @test as_polynomial((f, x, y) -> f(gcd(x, y)), 10x+10y, 5*(x^2-y^2), polyform=true) isa PolyForm
     @test repr(as_polynomial((f, x, y) -> f(gcd(x, y)), 10x+10y, 5*(x^2-y^2), polyform=true)) == repr(5x + 5y)
+
+
+    @test as_polynomial(x, y/z) do g, x, y
+        g(x+y)
+    end |> repr == "(y + x*z) / z"
 end