Add support for Differential(...)^0 (#1164)

* Add support for Differential(...)^0 * Add issue number * fix * fix * Don't need this var
JuliaSymbolics · Jun 8, 2024 · a09b05e · a09b05e
1 parent daaf8ee
commit a09b05e
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Showing 2 changed files with 9 additions and 1 deletion.
diff --git a/src/diff.jl b/src/diff.jl
@@ -51,7 +51,7 @@ is_derivative(x) = iscall(x) ? operation(x) isa Differential : false
 Base.:*(D1, D2::Differential) = D1 ∘ D2
 Base.:*(D1::Differential, D2) = D1 ∘ D2
 Base.:*(D1::Differential, D2::Differential) = D1 ∘ D2
-Base.:^(D::Differential, n::Integer) = _repeat_apply(D, n)
+Base.:^(D::Differential, n::Integer) = iszero(n) ? identity : _repeat_apply(D, n)
 
 Base.show(io::IO, D::Differential) = print(io, "Differential(", D.x, ")")
 

diff --git a/test/diff.jl b/test/diff.jl
@@ -370,4 +370,12 @@ let
     @test Symbolics.is_derivative(Symbolics.unwrap(D(X + 2a*Y)))
     @test !Symbolics.is_derivative(Symbolics.unwrap(D(X) + D(Y)))
     @test !Symbolics.is_derivative(Symbolics.unwrap(my_f(X, D(Y))))
+end
+
+# Zeroth derivative (#1163)
+let
+    @variables t
+    Dt = Differential(t)^0
+    @test isequal(Dt, identity)
+    test_equal(Dt(t + 2t^2), t + 2t^2)
 end