Remove Derivative export

Should only used when explicitly extending to new functions.

Author: HarrisonGrodin

README.md

@@ -269,7 +269,7 @@ t = Parameter(:t)
 x = Unknown(:x, dependents = [t])
 y = Unknown(:y, dependents = [t])
 z = Unknown(:z, dependents = [t])
-D = Differential(t) # Default of first derivative, Derivative(t,1)
+D = Differential(t)
 σ = Parameter(:σ)
 ρ = Parameter(:ρ)
 β = Parameter(:β)

src/differentials.jl

@@ -79,4 +79,4 @@ function calculate_jacobian(eqs,vars)
     Expression[Differential(vars[j])(eqs[i]) for i in 1:length(eqs), j in 1:length(vars)]
 end
 
-export Differential, Derivative, expand_derivatives, @Deriv, calculate_jacobian
+export Differential, expand_derivatives, @Deriv, calculate_jacobian

test/basic_variables_and_operations.jl

@@ -3,7 +3,7 @@ using Test
 
 @Param t σ ρ β
 @Unknown x(t) y(t) z(t)
-@Deriv D'~t # Default of first derivative, Derivative(t,1)
+@Deriv D'~t
 @Const c=0
 
 # Default values

test/derivatives.jl

@@ -15,11 +15,6 @@ dcsch = D(csch(t))
 # Chain rule
 dsinsin = D(sin(sin(t)))
 @test expand_derivatives(dsinsin) == cos(sin(t))*cos(t)
-# Binary
-dpow1 = Derivative(^, (x, y), Val(1))
-dpow2 = Derivative(^, (x, y), Val(2))
-@test dpow1 == y*x^(y-1)
-@test dpow2 == x^y*log(x)
 
 d1 = D(sin(t)*t)
 d2 = D(sin(t)*cos(t))
@@ -45,18 +40,3 @@ jac = ModelingToolkit.calculate_jacobian(sys)
 @Unknown a(t) b(a)
 @test D(b) ≠ Constant(0)
 
-
-# Regression test for PR #84
-let
-    # Define some variables
-    @Param t σ ρ β
-    @Unknown x(t) y(t) z(t)
-
-    f(x,y,z) = z*x+y
-    # This used to  seg fault, now raises MethodError
-    @test_throws MethodError Derivative(f, x, 1)
-    @Deriv D'~t
-    op = expand_derivatives(D(f(x,y,z)))
-    op.args[1].args[2].name == :z
-    op.args[1].args[2].diff.x.name == :t
-end

test/system_construction.jl

@@ -4,7 +4,7 @@ using Test
 # Define some variables
 @Param t σ ρ β
 @Unknown x(t) y(t) z(t)
-@Deriv D'~t # Default of first derivative, Derivative(t,1)
+@Deriv D'~t
 @Const c=0
 
 # Define a differential equation