From a299d739e131b69bfed5673253eb0ee4ec4ad392 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefanos=20Carlstr=C3=B6m?= <jagot@users.noreply.github.com>
Date: Mon, 12 Sep 2022 23:45:53 +0200
Subject: [PATCH] Fix comparison of zero NBodyMatrixElements (#19)

* Fix comparison of zero NBodyMatrixElements

* Bump version

* Update CI config
---
 .github/workflows/CI.yml      | 3 +--
 Project.toml                  | 2 +-
 src/nbody_matrix_elements.jl  | 1 +
 test/nbody_matrix_elements.jl | 6 ++++++
 4 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index f42222b..891a70e 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -13,8 +13,7 @@ jobs:
       matrix:
         version:
           - '1.6'
-          - '1.7'
-          - 'nightly'
+          - '1'
         os:
           - ubuntu-latest
           - macOS-latest
diff --git a/Project.toml b/Project.toml
index c9c2e2b..29bf669 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "EnergyExpressions"
 uuid = "f4b57a2e-27c7-11e9-0cb0-edd185b706f6"
 authors = ["Stefanos Carlström <stefanos.carlstrom@gmail.com>"]
-version = "0.1.0"
+version = "0.1.1"
 
 [deps]
 AtomicLevels = "10933b4c-d60f-11e8-1fc6-bd9035a249a1"
diff --git a/src/nbody_matrix_elements.jl b/src/nbody_matrix_elements.jl
index 528ad7a..465b24d 100644
--- a/src/nbody_matrix_elements.jl
+++ b/src/nbody_matrix_elements.jl
@@ -387,6 +387,7 @@ an expression with a reference, generated otherwise. It may not be
 performant. It may also fail on edge cases.
 """
 function compare(a::NBodyMatrixElement, op, b::NBodyMatrixElement; kwargs...)
+    iszero(a) && iszero(b) && return op(0, 0)
     ad,bd = map((a,b)) do o
         od = Dict{Vector{NBodyTermFactor},Number}()
         for term in o.terms
diff --git a/test/nbody_matrix_elements.jl b/test/nbody_matrix_elements.jl
index 96dce04..c8752f1 100644
--- a/test/nbody_matrix_elements.jl
+++ b/test/nbody_matrix_elements.jl
@@ -85,12 +85,18 @@
     @testset "NBodyMatrixElement" begin
         o = one(NBodyMatrixElement)
         z = zero(NBodyMatrixElement)
+        az = convert(NBodyMatrixElement, 0)
+        bz = 0convert(NBodyMatrixElement, 1)
 
         @test o == one(z)
         @test isone(o)
 
         @test z == zero(o)
         @test iszero(z)
+        @test z == az
+        @test z == bz
+        @test z ≈ az
+        @test z ≈ bz
 
 
         h = FieldFreeOneBodyHamiltonian()