add heaviside to lambdify (#412)

JuliaPy · Feb 28, 2021 · d32b3aa · d32b3aa · jverzani · Feb 28, 2021
1 parent d3fd8ef
commit d32b3aa
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Showing 3 changed files with 14 additions and 2 deletions.
diff --git a/Project.toml b/Project.toml
@@ -1,6 +1,6 @@
 name = "SymPy"
 uuid = "24249f21-da20-56a4-8eb1-6a02cf4ae2e6"
-version = "1.0.40"
+version = "1.0.41"
 
 
 [deps]

diff --git a/src/lambdify.jl b/src/lambdify.jl
@@ -62,7 +62,9 @@ fn_map = Dict(
               "StrictGreaterThan" => :(>),
               "GreaterThan" => :(>=),
               "Greater" => :(>),
-              "conjugate" => :conj
+    "conjugate" => :conj,
+    # not quite a match; NaN not θ(0) when evaluated at 0 w/o second argument
+    "Heaviside" => :((a...)  -> (a[1] < 0 ? 0.0 : (a[1] > 0 ? 1.0 : (length(a) > 1 ? a[2] : NaN))))
               )
 
 map_fn(key, fn_map) = haskey(fn_map, key) ? fn_map[key] : Symbol(key)

diff --git a/test/tests.jl b/test/tests.jl
@@ -718,4 +718,14 @@ end
     @vars n integer=true positive=true
     A = sympy.MatrixSymbol("A", n, n)
     @test inv(A) == A.I
+
+    ## issue #411 with Heaviside
+    @vars t
+    u = Heaviside(t)
+    λ = lambdify(u)
+    @test all((iszero(λ(-1)), isnan(λ(0)), isone(λ(1))))
+    u = Heaviside(t, 1)
+    λ = lambdify(u)
+    @test all((iszero(λ(-1)), isone(λ(0)), isone(λ(1))))
+
 end