added displacement

Author: nantonel

src/calculus/AffineAdd.jl

@@ -92,4 +92,5 @@ function permute(T::AffineAdd{L,D,S}, p::AbstractVector{Int}) where {L,D,S}
     return AffineAdd(A,T.d,S) 
 end
 
-
+displacement(A::AffineAdd{L,D,true})  where {L,D} =  A.d+displacement(A.A)
+displacement(A::AffineAdd{L,D,false}) where {L,D} = -A.d+displacement(A.A)

src/calculus/Sum.jl

@@ -116,3 +116,4 @@ function permute(S::Sum{M,N}, p::AbstractVector{Int}) where {M,N}
     AA = ([permute(A,p) for A in S.A]...) 
     return Sum(AA,S.bufC,S.bufD[p],M,N)
 end
+

src/properties.jl

@@ -16,7 +16,8 @@ export ndoms,
        is_full_column_rank,
        is_sliced,
        diag_AcA, 
-       diag_AAc
+       diag_AAc,
+       displacement
 
 
 """
@@ -267,6 +268,32 @@ true
 """
 is_sliced(L::AbstractOperator) = false
 
+"""
+`displacement(A::AbstractOperator)`
+
+Returns the displacement of the operator.
+
+```julia
+julia> A = AffineAdd(Eye(4),[1.;2.;3.;4.])
+I+d  ℝ^4 -> ℝ^4
+
+julia> displacement(A)
+4-element Array{Float64,1}:
+ 1.0
+ 2.0
+ 3.0
+ 4.0
+
+```
+"""
+function displacement(S::AbstractOperator) 
+    d = S*blockzeros(domainType(S),size(S,2))
+    if all(y -> y == d[1], d ) 
+        return d[1]
+    else
+        return d
+    end
+end
 
 import Base: convert
 function convert(::Type{T}, dom::Type, dim_in::Tuple, L::T) where {T <: AbstractOperator}