Merge pull request #346 from JuliaSymbolics/myb/opt

Optimized ordering computation

Author: YingboMa

src/ordering.jl

@@ -10,7 +10,11 @@
 
 arglength(a) = length(arguments(a))
 function <ₑ(a, b)
-    if !istree(a) && !istree(b)
+    if a isa Term && (b isa Symbolic && !(b isa Term))
+        return false
+    elseif  b isa Term && (a isa Symbolic && !(a isa Term))
+        return true
+    elseif !istree(a) && !istree(b)
         T = typeof(a)
         S = typeof(b)
         return T===S ? (T <: Number ? isless(a, b) : hash(a) < hash(b)) : nameof(T) < nameof(S)

test/order.jl

@@ -5,15 +5,15 @@ SymbolicUtils.show_simplified[] = false
 
 @syms a b c
 
-function istotal(x,y)
+function istotal(x, y)
     #either
     if x <ₑ y
         return !(y <ₑ x)
     elseif y <ₑ x
         return !(x <ₑ y) # already tested
     else
         # neither, equal
-        return true
+        return isequal(x, y)
     end
 end
 
@@ -78,8 +78,7 @@ end
 @testset "small terms" begin
     # this failing was a cause of a nasty stackoverflow #82
     @syms a
-    @test Term(^, [a, -1]) <ₑ (a + 2)
-    @test !((a + 2) <ₑ Term(^, [a, -1]))
+    istotal(Term(^, [a, -1]), (a + 2))
 end
 
 @testset "transitivity" begin