widen signature for simplify, add not to solve documentation (#344)

Project.toml

@@ -1,6 +1,6 @@
 name = "SymPy"
 uuid = "24249f21-da20-56a4-8eb1-6a02cf4ae2e6"
-version = "1.0.19"
+version = "1.0.20"
 
 
 [deps]

README.md

@@ -21,7 +21,7 @@ easier.
 
 The [tutorial](examples/tutorial.md) provides an overview. It is
 viewable as an `IJulia` notebook
-[here](http://nbviewer.ipython.org/github/JuliaPy/SymPy.jl/blob/master/examples/tutorial.ipynb). In addition, most of the SymPy tutorial has the `julia` counterparts illustrated starting from [index.html](http://htmlpreview.github.io/?https://github.com/JuliaPy/SymPy.jl/blob/master/examples/index.html)
+[here](http://nbviewer.ipython.org/github/JuliaPy/SymPy.jl/blob/master/examples/tutorial.ipynb). In addition, most of the SymPy tutorial has the `julia` counterparts illustrated starting from [index.html](http://htmlpreview.github.io/?https://github.com/JuliaPy/SymPy.jl/blob/master/examples/index.html).
 
 ### Installation
 

src/mathfuns.jl

@@ -78,6 +78,23 @@ end
 
 
 ## Add interfaces for solve, nonlinsolve when vector of equations passed in
+"""
+    solve
+
+Use `solve` to solve algebraic equations. 
+
+Examples:
+```
+@vars x y a b c d
+solve(x^2 + 2x + 1, x) # [-1]
+solve(x^2 + 2a*x + a^2, x) # [-a]
+solve([a*x + b*y-3, c*x + b*y - 1], [x,y]) # Dict(y => (a - 3*c)/(b*(a - c)),x => 2/(a - c))
+```
+
+!!! Note
+   A very nice example using `solve` is a [blog](https://newptcai.github.io/euclidean-plane-geometry-with-julia.html) entry on [Napolean's theorem](https://en.wikipedia.org/wiki/Napoleon%27s_theorem) by Xing Shi Cai.
+"""
+solve() = ()
 solve(V::Vector{T}, args...; kwargs...) where {T <: SymbolicObject} =
     sympy.solve(V, args...; kwargs...)
 

src/utils.jl

@@ -111,6 +111,15 @@ subs(;kwargs...)                      = ex -> subs(ex; kwargs...)
 subs(dict::Dict; kwargs...)           = ex -> subs(ex, dict...; kwargs...)
 subs(d::Pair...; kwargs...)           = ex -> subs(ex, [(p.first, p.second) for p in d]...; kwargs...)
 
+## simplify(ex::SymbolicObject, ...) is exported
+"""
+    simplify
+
+SymPy has dozens of functions to perform various kinds of simplification. There is also one general function called `simplify` that attempts to apply all of these functions in an intelligent way to arrive at the simplest form of an expression. (See [Simplification](https://docs.sympy.org/latest/tutorial/simplification.html) for details on `simplify` and other related functionality).
+
+For non-symbolic expressions, `simplify` returns its first argument.
+"""
+simplify(x,args...;kwargs...) = x
 
 ##################################################
 # avoid type piracy. After we call `pytype` mappings, some

test/tests.jl

@@ -130,6 +130,13 @@ import PyCall
     ex = line(10)
     @test ex(sol) == ex(sol...) == 11
 
+    ## Simplify (issue 343)
+    @vars x
+    @test simplify(sin(x)^2 + cos(x)^2) == 1
+    @test simplify(sympy.gamma(x)/sympy.gamma(x-2)) == (x-1)*(x-2)
+    _ones = (1, 1.0, big"1", "1", one)
+    @test simplify.(_ones) == _ones
+
     ## Conversion
     x = Sym("x")
     p = x.subs(x,pi)