Clean up conversions between special and/or annotated matrix types.

JuliaLang · Sep 26, 2017 · ba3c22d · ba3c22d
1 parent 76bf3a7
commit ba3c22d
Showing 1 changed file with 34 additions and 64 deletions.
diff --git a/base/linalg/special.jl b/base/linalg/special.jl
@@ -2,7 +2,10 @@
 
 # Methods operating on different special matrix types
 
+
 # Interconversion between special matrix types
+
+# conversions from Diagonal to other special matrix types
 convert(::Type{Bidiagonal}, A::Diagonal) =
     Bidiagonal(A.diag, fill!(similar(A.diag, length(A.diag)-1), 0), :U)
 convert(::Type{SymTridiagonal}, A::Diagonal) =
@@ -11,86 +14,53 @@ convert(::Type{Tridiagonal}, A::Diagonal) =
     Tridiagonal(fill!(similar(A.diag, length(A.diag)-1), 0), A.diag,
                 fill!(similar(A.diag, length(A.diag)-1), 0))
 
-function convert(::Type{Diagonal}, A::Union{Bidiagonal, SymTridiagonal})
-    if !iszero(A.ev)
+# conversions from Bidiagonal to other special matrix types
+convert(::Type{Diagonal}, A::Bidiagonal) =
+    iszero(A.ev) ? Diagonal(A.dv) :
         throw(ArgumentError("matrix cannot be represented as Diagonal"))
-    end
-    Diagonal(A.dv)
-end
-
-function convert(::Type{SymTridiagonal}, A::Bidiagonal)
-    if !iszero(A.ev)
+convert(::Type{SymTridiagonal}, A::Bidiagonal) =
+    iszero(A.ev) ? SymTridiagonal(A.dv, A.ev) :
         throw(ArgumentError("matrix cannot be represented as SymTridiagonal"))
-    end
-    SymTridiagonal(A.dv, A.ev)
-end
-
-convert(::Type{Tridiagonal}, A::Bidiagonal{T}) where {T} =
+convert(::Type{Tridiagonal}, A::Bidiagonal) =
     Tridiagonal(A.uplo == 'U' ? fill!(similar(A.ev), 0) : A.ev, A.dv,
                 A.uplo == 'U' ? A.ev : fill!(similar(A.ev), 0))
 
-function convert(::Type{Bidiagonal}, A::SymTridiagonal)
-    if !iszero(A.ev)
+# conversions from SymTridiagonal to other special matrix types
+convert(::Type{Diagonal}, A::SymTridiagonal) =
+    iszero(A.ev) ? Diagonal(A.dv) :
+        throw(ArgumentError("matrix cannot be represented as Diagonal"))
+convert(::Type{Bidiagonal}, A::SymTridiagonal) =
+    iszero(A.ev) ? Bidiagonal(A.dv, A.ev, :U) :
         throw(ArgumentError("matrix cannot be represented as Bidiagonal"))
-    end
-    Bidiagonal(A.dv, A.ev, :U)
-end
+convert(::Type{Tridiagonal}, A::SymTridiagonal) =
+    Tridiagonal(copy(A.ev), A.dv, A.ev)
 
-function convert(::Type{Diagonal}, A::Tridiagonal)
-    if !(iszero(A.dl) && iszero(A.du))
+# conversions from Tridiagonal to other special matrix types
+convert(::Type{Diagonal}, A::Tridiagonal) =
+    iszero(A.dl) && iszero(A.du) ? Diagonal(A.d) :
         throw(ArgumentError("matrix cannot be represented as Diagonal"))
-    end
-    Diagonal(A.d)
-end
-
-function convert(::Type{Bidiagonal}, A::Tridiagonal)
-    if iszero(A.dl)
-        return Bidiagonal(A.d, A.du, :U)
-    elseif iszero(A.du)
-        return Bidiagonal(A.d, A.dl, :L)
-    else
+convert(::Type{Bidiagonal}, A::Tridiagonal) =
+    iszero(A.dl) ? Bidiagonal(A.d, A.du, :U) :
+    iszero(A.du) ? Bidiagonal(A.d, A.dl, :L) :
         throw(ArgumentError("matrix cannot be represented as Bidiagonal"))
-    end
-end
-
-function convert(::Type{SymTridiagonal}, A::Tridiagonal)
-    if A.dl != A.du
+convert(::Type{SymTridiagonal}, A::Tridiagonal) =
+    A.dl == A.du ? SymTridiagonal(A.d, A.dl) :
         throw(ArgumentError("matrix cannot be represented as SymTridiagonal"))
-    end
-    SymTridiagonal(A.d, A.dl)
-end
-
-function convert(::Type{Tridiagonal}, A::SymTridiagonal)
-    Tridiagonal(copy(A.ev), A.dv, A.ev)
-end
 
-function convert(::Type{Diagonal}, A::AbstractTriangular)
-    if !isdiag(A)
+# conversions from AbstractTriangular to special matrix types
+convert(::Type{Diagonal}, A::AbstractTriangular) =
+    isdiag(A) ? Diagonal(diag(A)) :
         throw(ArgumentError("matrix cannot be represented as Diagonal"))
-    end
-    Diagonal(diag(A))
-end
-
-function convert(::Type{Bidiagonal}, A::AbstractTriangular)
-    if isbanded(A, 0, 1) # is upper bidiagonal
-        return Bidiagonal(diag(A), diag(A, 1), :U)
-    elseif isbanded(A, -1, 0) # is lower bidiagonal
-        return Bidiagonal(diag(A), diag(A, -1), :L)
-    else
+convert(::Type{Bidiagonal}, A::AbstractTriangular) =
+    isbanded(A, 0, 1) ? Bidiagonal(diag(A), diag(A,  1), :U) : # is upper bidiagonal
+    isbanded(A, -1, 0) ? Bidiagonal(diag(A), diag(A, -1), :L) : # is lower bidiagonal
         throw(ArgumentError("matrix cannot be represented as Bidiagonal"))
-    end
-end
-
 convert(::Type{SymTridiagonal}, A::AbstractTriangular) =
     convert(SymTridiagonal, convert(Tridiagonal, A))
-
-function convert(::Type{Tridiagonal}, A::AbstractTriangular)
-    if isbanded(A, -1, 1) # is tridiagonal
-        return Tridiagonal(diag(A, -1), diag(A), diag(A, 1))
-    else
+convert(::Type{Tridiagonal}, A::AbstractTriangular) =
+    isbanded(A, -1, 1) ? Tridiagonal(diag(A, -1), diag(A), diag(A, 1)) : # is tridiagonal
         throw(ArgumentError("matrix cannot be represented as Tridiagonal"))
-    end
-end
+
 
 # Constructs two method definitions taking into account (assumed) commutativity
 # e.g. @commutative f(x::S, y::T) where {S,T} = x+y is the same is defining