Fix JuliaLang#10739, implement isdiag method

pwl · Apr 27, 2015 · b7f0c03 · b7f0c03
1 parent 102e840
commit b7f0c03
Show file tree

Hide file tree

Showing 7 changed files with 27 additions and 3 deletions.
diff --git a/base/exports.jl b/base/exports.jl
@@ -634,6 +634,7 @@ export
  givens,
  hessfact!,
  hessfact,
+ isdiag,
  ishermitian,
  isposdef!,
  isposdef,

diff --git a/base/linalg.jl b/base/linalg.jl
@@ -69,6 +69,7 @@ export
  gradient,
  hessfact,
  hessfact!,
+ isdiag,
  ishermitian,
  isposdef,
  isposdef!,

diff --git a/base/linalg/generic.jl b/base/linalg/generic.jl
@@ -308,8 +308,11 @@ function istril(A::AbstractMatrix)
  return true
 end
 
+isdiag(A::AbstractMatrix) = istril(A) && istriu(A)
+
 istriu(x::Number) = true
 istril(x::Number) = true
+isdiag(x::Number) = true
 
 linreg{T<:Number}(X::StridedVecOrMat{T}, y::Vector{T}) = [ones(T, size(X,1)) X] \ y
 

diff --git a/doc/stdlib/linalg.rst b/doc/stdlib/linalg.rst
@@ -630,6 +630,10 @@ Linear algebra functions in Julia are largely implemented by calling functions f
 
  Test whether a matrix is upper triangular.
 
+.. function:: isdiag(A) -> Bool
+
+ Test whether a matrix is diagonal.
+
 .. function:: ishermitian(A) -> Bool
 
  Test whether a matrix is Hermitian.

diff --git a/test/arrayops.jl b/test/arrayops.jl
@@ -806,6 +806,17 @@ end
 @test_throws ArgumentError flipdim(1:10, -1)
 @test isequal(flipdim(Array(Int,0,0),1), Array(Int,0,0)) # issue #5872
 
+# isdiag, istril, istriu
+@test isdiag(3)
+@test istril(4)
+@test istriu(5)
+@test !isdiag([1 2; 3 4])
+@test !istril([1 2; 3 4])
+@test !istriu([1 2; 3 4])
+@test isdiag([1 0; 0 4])
+@test istril([1 0; 3 4])
+@test istriu([1 2; 0 4])
+
 # issue 4228
 A = [[i i; i i] for i=1:2]
 @test cumsum(A) == Any[[1 1; 1 1], [3 3; 3 3]]

diff --git a/test/linalg/bidiag.jl b/test/linalg/bidiag.jl
@@ -78,8 +78,8 @@ for relty in (Float32, Float64, BigFloat), elty in (relty, Complex{relty})
  end
 end
 
-#Issue 10742
+# Issue 10742 and similar
 let A = Bidiagonal([1,2,3], [0,0], true)
  @test istril(A)
+ @test isdiag(A)
 end
-
diff --git a/test/linalg/triangular.jl b/test/linalg/triangular.jl
@@ -275,6 +275,10 @@ for eltya in (Float32, Float64, Complex64, Complex128, BigFloat, Int)
  end
 end
 
-# Issue 10742
+# Issue 10742 and similar
 @test istril(UpperTriangular(diagm([1,2,3,4])))
 @test istriu(LowerTriangular(diagm([1,2,3,4])))
+@test isdiag(UpperTriangular(diagm([1,2,3,4])))
+@test isdiag(LowerTriangular(diagm([1,2,3,4])))
+@test !isdiag(UpperTriangular(rand(4, 4)))
+@test !isdiag(LowerTriangular(rand(4, 4)))