Consistency of return type for matrix functions

base/linalg/dense.jl

@@ -189,7 +189,9 @@ expm(x::Number) = exp(x)
 ## "Functions of Matrices: Theory and Computation", SIAM
 function expm!{T<:BlasFloat}(A::StridedMatrix{T})
     n = chksquare(A)
-    n<2 && return exp(A)
+    if ishermitian(A)
+        return full(expm(Hermitian(A)))
+    end
     ilo, ihi, scale = LAPACK.gebal!('B', A)    # modifies A
     nA   = norm(A, 1)
     I    = eye(T,n)
@@ -278,10 +280,12 @@ function rcswap!{T<:Number}(i::Integer, j::Integer, X::StridedMatrix{T})
     end
 end
 
+expm(x::Number) = exp(x)
+
 function logm(A::StridedMatrix)
     # If possible, use diagonalization
     if ishermitian(A)
-        return logm(Hermitian(A))
+        return full(logm(Hermitian(A)))
     end
 
     # Use Schur decomposition
@@ -313,12 +317,13 @@ function logm(A::StridedMatrix)
         return retmat
     end
 end
+
 logm(a::Number) = (b = log(complex(a)); imag(b) == 0 ? real(b) : b)
 logm(a::Complex) = log(a)
 
 function sqrtm{T<:Real}(A::StridedMatrix{T})
     if issym(A)
-        return sqrtm(Symmetric(A))
+        return full(sqrtm(Symmetric(A)))
     end
     n = chksquare(A)
     SchurF = schurfact(complex(A))
@@ -328,13 +333,14 @@ function sqrtm{T<:Real}(A::StridedMatrix{T})
 end
 function sqrtm{T<:Complex}(A::StridedMatrix{T})
     if ishermitian(A)
-        return sqrtm(Hermitian(A))
+        return full(sqrtm(Hermitian(A)))
     end
     n = chksquare(A)
     SchurF = schurfact(A)
     R = full(sqrtm(UpperTriangular(SchurF[:T])))
     SchurF[:vectors]*R*SchurF[:vectors]'
 end
+
 sqrtm(a::Number) = (b = sqrt(complex(a)); imag(b) == 0 ? real(b) : b)
 sqrtm(a::Complex) = sqrt(a)
 

base/linalg/eigen.jl

@@ -23,7 +23,7 @@ function getindex(A::Union{Eigen,GeneralizedEigen}, d::Symbol)
     throw(KeyError(d))
 end
 
-isposdef(A::Union{Eigen,GeneralizedEigen}) = all(A.values .> 0)
+isposdef(A::Union{Eigen,GeneralizedEigen}) = isreal(A.values) && all(A.values .> 0)
 
 function eigfact!{T<:BlasReal}(A::StridedMatrix{T}; permute::Bool=true, scale::Bool=true)
     n = size(A, 2)

base/linalg/symmetric.jl

@@ -126,14 +126,57 @@ function svdvals!{T<:Real,S}(A::Union{Hermitian{T,S}, Symmetric{T,S}, Hermitian{
 end
 
 #Matrix-valued functions
-expm{T<:Real}(A::RealHermSymComplexHerm{T}) = (F = eigfact(A); F.vectors*Diagonal(exp(F.values))*F.vectors')
-function logm{T<:Real}(A::RealHermSymComplexHerm{T})
-    F = eigfact(A)
-    isposdef(F) && return F.vectors*Diagonal(log(F.values))*F.vectors'
-    return F.vectors*Diagonal(log(complex(F.values)))*F.vectors'
+function expm(A::Symmetric)
+    F = eigfact(full(A))
+    return Symmetric((F.vectors * Diagonal(exp(F.values))) * F.vectors')
 end
-function sqrtm{T<:Real}(A::RealHermSymComplexHerm{T})
-    F = eigfact(A)
-    isposdef(F) && return F.vectors*Diagonal(sqrt(F.values))*F.vectors'
-    return F.vectors*Diagonal(sqrt(complex(F.values)))*F.vectors'
+function expm{T}(A::Hermitian{T})
+    n = chksquare(A)
+    F = eigfact(full(A))
+    retmat = (F.vectors * Diagonal(exp(F.values))) * F.vectors'
+    if T <: Real
+        return real(Hermitian(retmat))
+    else
+        for i = 1:n
+            retmat[i,i] = real(retmat[i,i])
+        end
+        return Hermitian(retmat)
+    end
+end
+
+for (funm, func) in ([:logm,:log], [:sqrtm,:sqrt])
+
+    @eval begin
+
+        function ($funm)(A::Symmetric)
+            F = eigfact(full(A))
+            if isposdef(F)
+                retmat = (F.vectors * Diagonal(($func)(F.values))) * F.vectors'
+            else
+                retmat = (F.vectors * Diagonal(($func)(complex(F.values)))) * F.vectors'
+            end
+            return Symmetric(retmat)
+        end
+
+        function ($funm){T}(A::Hermitian{T})
+            n = chksquare(A)
+            F = eigfact(A)
+            if isposdef(F)
+                retmat = (F.vectors * Diagonal(($func)(F.values))) * F.vectors'
+                if T <: Real
+                    return Hermitian(retmat)
+                else
+                    for i = 1:n
+                        retmat[i,i] = real(retmat[i,i])
+                    end
+                    return Hermitian(retmat)
+                end
+            else
+                retmat = (F.vectors * Diagonal(($func)(complex(F.values)))) * F.vectors'
+                return retmat
+            end
+        end
+
+    end
+
 end