fix substitution variable order (#490)

* fix substitution variable order

* fix doctests

Project.toml

@@ -1,6 +1,6 @@
 name = "SymPy"
 uuid = "24249f21-da20-56a4-8eb1-6a02cf4ae2e6"
-version = "1.1.7"
+version = "1.1.8"
 
 [deps]
 CommonEq = "3709ef60-1bee-4518-9f2f-acd86f176c50"

docs/src/Tutorial/basic_operations.md

@@ -515,7 +515,7 @@ julia> ex = sin(x)^2 + x^2
 x  + sin (x)
 
 julia> body = convert(Expr, ex)
-:(x ^ 2 + sin(x) ^ 2)
+:(SymPy.__POW__(x, 2) + SymPy.__POW__(sin(x), 2))
 
 julia> syms = Symbol.(free_symbols(ex))
 1-element Vector{Symbol}:

docs/src/Tutorial/intro.md

@@ -446,6 +446,7 @@ spherical Bessel function $j_\nu(z)$.
 ```jldoctest intro
 julia> using SpecialFunctions
 
+
 julia> @syms ν z
 (ν, z)
 

docs/src/Tutorial/matrices.md

@@ -472,7 +472,6 @@ julia> using Test
 
 julia> @test_throws  Exception M1^-1
 Test Passed
-  Expression: M1 ^ -1
       Thrown: PyCall.PyError
 
 ```
@@ -798,7 +797,7 @@ There is no reason  to,  but generic `Julia` methods  could be used:
 
 ```jldoctest matrices
 julia> out  = lu(A)
-LU{Sym, Matrix{Sym}}
+LU{Sym, Matrix{Sym}, Vector{Int64}}
 L factor:
 2×2 Matrix{Sym}:
    1  0

docs/src/Tutorial/simplification.md

@@ -71,6 +71,7 @@ x - 1
 
 julia> using SpecialFunctions
 
+
 julia> simplify(gamma(x)/gamma(x - 2))
 (x - 2)⋅(x - 1)
 

docs/src/Tutorial/solvers.md

@@ -228,6 +228,7 @@ julia> aug = [A b]
  1  1  2  3
 
 julia> linsolve(aug, (x,y,z)) # {(-y - 1, y, 2)};
+{(-y - 1, y, 2)}
 
 ```
 

src/lambdify.jl

@@ -149,7 +149,7 @@ x ⋅sin(x)
 julia> fn = lambdify(ex);
 
 julia> fn(pi)
-1.2086779438644711e-15
+0.0
 
 julia> ex = x + 2y + 3z
 x + 2⋅y + 3⋅z

src/mathfuns.jl

@@ -215,10 +215,8 @@ julia> dsolve(eqns, ics = Dict(x(0) => 1, y(0) => 2))
  Eq(x(t), 3*exp(t)/2 - exp(-t)/2)
  Eq(y(t), 3*exp(t)/2 + exp(-t)/2)
 
-julia> eqns = [∂(∂(x(t))) ~ 0, ∂(∂(y(t))) ~ -g]
-2-element Vector{Sym}:
-  Eq(Derivative(x(t), (t, 2)), 0)
- Eq(Derivative(y(t), (t, 2)), -g)
+julia> eqns = (∂(∂(x(t))) ~ 0, ∂(∂(y(t))) ~ -g)
+(Eq(Derivative(x(t), (t, 2)), 0), Eq(Derivative(y(t), (t, 2)), -g))
 
 julia> dsolve(eqns)  # can't solve for initial conditions though! (NotAlgebraic)
 2-element Vector{Sym}:

src/utils.jl

@@ -49,7 +49,7 @@ end
 
 ## without specification, variables to substitute for come from ordering of `free_symbols`:
 function (ex::Sym)(args...)
-    xs = ex.free_symbols
+    xs = free_symbols(ex)
     for (var, val) in zip(xs, args)
         ex = ex.subs(var, Sym(val))
     end

test/tests.jl

@@ -848,6 +848,11 @@ end
     ## Issue #433 add sympy docstrings, clean up docstring
     sprint(io -> show(io, SymPy.Doc(:sin)))
 
+    ## Issue 456 use free_symbols() not .free_symbols in call
+    @syms x y
+    df = sympy.diff(sin(y-x),x)
+    @test df(x, PI/2) == -sin(x)
+
 end
 
 @test SymPy.convert_expr(sympy.Indexed(sympy.IndexedBase(:x), 1, -2)) == :(x[1, -2])