Clean up examples

Author: HarrisonGrodin

README.md

@@ -28,10 +28,9 @@ and parameters. Therefore we label them as follows:
 using ModelingToolkit
 
 # Define some variables
-@Param t
+@Param t σ ρ β
 @Unknown x(t) y(t) z(t)
 @Deriv D'~t
-@Param σ ρ β
 ```
 
 Then we build the system:
@@ -259,10 +258,9 @@ is accessible via a function-based interface. This means that all macros are
 syntactic sugar in some form. For example, the variable construction:
 
 ```julia
-@Param t
+@Param t σ ρ β
 @Unknown x(t) y(t) z(t)
 @Deriv D'~t
-@Param σ ρ β
 ```
 
 is syntactic sugar for:

src/variables.jl

@@ -8,10 +8,10 @@ end
 Variable(name; subtype::Symbol, dependents::Vector{Variable} = Variable[]) =
     Variable(name, subtype, nothing, dependents)
 
-Parameter(name,args...;kwargs...) = Variable(name,args...;subtype=:Parameter,kwargs...)
-Unknown(name,args...;kwargs...) = Variable(name,args...;subtype=:Unknown,kwargs...)
+Parameter(name; kwargs...) = Variable(name; subtype=:Parameter, kwargs...)
+Unknown(name, ;kwargs...) = Variable(name; subtype=:Unknown, kwargs...)
 
-export Variable, Parameter, Constant, Unknown, @Param, @Const, @Unknown
+export Variable, Unknown, Parameter, Constant, @Unknown, @Param, @Const
 
 
 Base.copy(x::Variable) = Variable(x.name, x.subtype, x.diff, x.dependents)

test/basic_variables_and_operations.jl

@@ -1,11 +1,9 @@
 using ModelingToolkit
 using Test
 
-@Param t
+@Param t σ ρ β
 @Unknown x(t) y(t) z(t)
-
 @Deriv D'~t # Default of first derivative, Derivative(t,1)
-@Param σ ρ β
 @Const c=0
 
 # Default values

test/derivatives.jl

@@ -2,9 +2,8 @@ using ModelingToolkit
 using Test
 
 # Derivatives
-@Param t
+@Param t σ ρ β
 @Unknown x(t) y(t) z(t)
-@Param σ ρ β
 @Deriv D'~t
 dsin = D(sin(t))
 expand_derivatives(dsin)

test/system_construction.jl

@@ -2,10 +2,9 @@ using ModelingToolkit
 using Test
 
 # Define some variables
-@Param t
+@Param t σ ρ β
 @Unknown x(t) y(t) z(t)
 @Deriv D'~t # Default of first derivative, Derivative(t,1)
-@Param σ ρ β
 @Const c=0
 
 # Define a differential equation