Merge pull request #306 from JuliaSymbolics/myb/div

Preserve rational if possible

Author: YingboMa

src/types.jl

@@ -200,8 +200,7 @@ struct FnType{X<:Tuple,Y} end
 
 function (f::Symbolic)(args...)
     error("Sym $f is not callable. " *
-          "Use @syms $f(var1, var2,...) to create it as a callable. " *
-          "See ?@fun for more options")
+          "Use @syms $f(var1, var2,...) to create it as a callable.")
 end
 
 """
@@ -494,7 +493,7 @@ end
 function show_mul(io, args)
     length(args) == 1 && return print_arg(io, *, args[1])
 
-    paren_scalar = args[1] isa Complex || args[1] isa Rational || (args[1] isa Number && !isfinite(args[1]))
+    paren_scalar = (args[1] isa Complex && !_iszero(imag(args[1]))) || args[1] isa Rational || (args[1] isa Number && !isfinite(args[1]))
     minus = args[1] isa Number && args[1] == -1
     unit = args[1] isa Number && args[1] == 1
     nostar = !paren_scalar && args[1] isa Number && !(args[2] isa Number)
@@ -831,7 +830,7 @@ end
 
 \(a::Number, b::SN) = b / a
 
-/(a::SN, b::Number) = inv(b) * a
+/(a::SN, b::Number) = (b isa Integer ? 1//b : inv(b)) * a
 
 //(a::Union{SN, Number}, b::SN) = a / b
 

test/basics.jl

@@ -123,6 +123,7 @@ end
     @test isequal(w == 0, Term{Bool}(==, [w, 0]))
 
     @eqtest x // 5 == (1 // 5) * x
+    @eqtest (1//2 * x) / 5 == (1 // 10) * x
     @eqtest x // Int16(5) == Rational{Int16}(1, 5) * x
     @eqtest 5 // x == 5 / x
     @eqtest x // a == x / a

test/fuzz.jl

@@ -6,17 +6,20 @@ seed!(6174)
 @testset "Fuzz test" begin
     @time @testset "expand fuzz" begin
         for i=1:500
+            i % 100 == 0 && @info "expand fuzz" iter=i
             fuzz_test(5, num_spec, SymbolicUtils.expand; min_depth=3)
         end
     end
     @time @testset "num fuzz" begin
         for i=1:1500
+            i % 100 == 0 && @info "num fuzz" iter=i
             fuzz_test(5, num_spec)
         end
     end
     @time @testset "bool fuzz" begin
         for i=1:500
             seed!(i)
+            i % 100 == 0 && @info "bool fuzz" iter=i
             fuzz_test(5, bool_spec)
         end
     end