Allow non-zero fill! if all the entries are in bands (#479)

* Allow non-zero fill! if all the entries are in bands

* v1.9.4

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "BandedMatrices"
 uuid = "aae01518-5342-5314-be14-df237901396f"
-version = "1.9.3"
+version = "1.9.4"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/banded/BandedMatrix.jl

@@ -857,8 +857,19 @@ svdvals(A::BandedMatrix) = svdvals!(copy(A))
 
 ## ALgebra and other functions
 
+"""
+allinbands(A)
+
+returns true if there are no entries outside the bands.
+"""
+function allinbands(A)
+    m,n = size(A)
+    l,u = bandwidths(A)
+    m ≤ l+1 && n ≤ u+1
+end
+
 function fill!(A::BandedMatrix, x)
-    iszero(x) || throw(BandError(A))
+    iszero(x) || allinbands(A) || throw(BandError(A))
     fill!(A.data, x)
     A
 end

test/test_banded.jl

@@ -253,23 +253,30 @@ include("mymatrix.jl")
     end
 
     @testset "BandedMatrix interface" begin
-        # check that col/rowstop is ≥ 0
-        let A = brand(3,4,-2,2)
-            @test BandedMatrices.colstop(A, 1) == BandedMatrices.colstop(A, 2) == 0
-            @test BandedMatrices.colstop(A, 3) == 1
-        end
+        @testset "check that col/rowstop is ≥ 0" begin
+            let A = brand(3,4,-2,2)
+                @test BandedMatrices.colstop(A, 1) == BandedMatrices.colstop(A, 2) == 0
+                @test BandedMatrices.colstop(A, 3) == 1
+            end
 
-        let A = brand(3,4,2,-2)
-            @test BandedMatrices.rowstop(A, 1) == BandedMatrices.rowstop(A, 2) == 0
-            @test BandedMatrices.rowstop(A, 3) == 1
+            let A = brand(3,4,2,-2)
+                @test BandedMatrices.rowstop(A, 1) == BandedMatrices.rowstop(A, 2) == 0
+                @test BandedMatrices.rowstop(A, 3) == 1
+            end
         end
 
-        # Test fill!
-        let B = brand(10,10,1,4)
-            @test_throws BandError fill!(B, 1.0)
-            @test_throws BandError fill!(B, 1)
-            fill!(B, 0)
-            @test Matrix(B) == zeros(10,10)
+        @testset "fill!" begin
+            let B = brand(10,10,1,4)
+                @test_throws BandError fill!(B, 1.0)
+                @test_throws BandError fill!(B, 1)
+                fill!(B, 0)
+                @test Matrix(B) == zeros(10,10)
+            end
+
+            let B = brand(2,3,1,4)
+                fill!(B, 1)
+                @test Matrix(B) == ones(2,3)
+            end
         end
     end