Update result.jl (#109)

* Update result.jl

close #108

* Format

* Test on empty matrices too

* Fix

---------

Co-authored-by: Guillaume Dalle <22795598+gdalle@users.noreply.github.com>

Author: amontoison

src/result.jl

@@ -279,7 +279,7 @@ function TreeSetColoringResult(
     reverse_bfs_orders = [Tuple{Int,Int}[] for i in 1:ntrees]
 
     # nvmax is the number of vertices of the biggest tree in the forest
-    nvmax = mapreduce(length, max, vertices_by_tree)
+    nvmax = mapreduce(length, max, vertices_by_tree; init=0)
 
     # Create a queue with a fixed size nvmax
     queue = Vector{Int}(undef, nvmax)

test/random.jl

@@ -12,14 +12,14 @@ using Test
 rng = StableRNG(63)
 
 asymmetric_params = vcat(
-    [(10, 20, p) for p in (0.1:0.1:0.5)],
-    [(20, 10, p) for p in (0.1:0.1:0.5)],
+    [(10, 20, p) for p in (0.0:0.1:0.5)],
+    [(20, 10, p) for p in (0.0:0.1:0.5)],
     [(100, 200, p) for p in (0.01:0.01:0.05)],
     [(200, 100, p) for p in (0.01:0.01:0.05)],
 )
 
 symmetric_params = vcat(
-    [(10, p) for p in (0.1:0.1:0.5)], #
+    [(10, p) for p in (0.0:0.1:0.5)], #
     [(100, p) for p in (0.01:0.01:0.05)],
 )
 

test/utils.jl

@@ -98,7 +98,7 @@ function test_coloring_decompression(
         end
 
         @testset "Linear system decompression" begin
-            if structure == :symmetric
+            if structure == :symmetric && count(!iszero, A) > 0  # sparse factorization cannot handle empty matrices
                 linresult = LinearSystemColoringResult(sparse(A), color, Float64)
                 @test decompress(float.(B), linresult) ≈ A0
                 @test decompress!(respectful_similar(float.(A)), float.(B), linresult) ≈ A0