Fix hcat and vcat for variables arguments

src/LinearOperators.jl

@@ -348,7 +348,6 @@ end
 -(op :: AbstractLinearOperator, x :: Number) = op + (-x)
 -(x :: Number, op :: AbstractLinearOperator) = x + (-op)
 
-
 # Utility functions.
 
 """
@@ -576,7 +575,6 @@ function opDiagonal(nrow :: Int, ncol :: Int, d :: AbstractVector{T}) where T
   LinearOperator{T,F1,F2,F3}(nrow, ncol, false, false, prod, tprod, ctprod)
 end
 
-
 hcat(A :: AbstractLinearOperator, B :: AbstractMatrix) = hcat(A, LinearOperator(B))
 
 hcat(A :: AbstractMatrix, B :: AbstractLinearOperator) = hcat(LinearOperator(A), B)
@@ -599,13 +597,53 @@ function hcat(A :: AbstractLinearOperator, B :: AbstractLinearOperator)
 end
 
 function hcat(ops :: OperatorOrMatrix...)
-  op = ops[1]
-  for i = 2:length(ops)
-    op = [op ops[i]]
+  nops = length(ops)
+  nrow = size(ops[1], 1)
+  for i = 2:nops
+    size(ops[i], 1) == nrow || throw(LinearOperatorException("hcat: inconsistent row sizes"))
+  end
+  ncol = sum(size(ops[i], 2) for i = 1:nops)
+  S = eltype(ops[1])
+  for i = 2:nops
+    S = promote_type(S, eltype(ops[i]))
   end
-  return op
-end
 
+  prod = @closure v -> begin
+    Av = zeros(S, nrow)
+    k = 0
+    for i = 1:nops
+      s = size(ops[i], 2)
+      Av .+= ops[i] * v[k+1:k+s]
+      k += s
+    end
+    return Av
+  end
+  function tprod(v)
+    Atv = zeros(S, ncol)
+    k = 0
+    for i = 1:nops
+      s = size(ops[i], 2)
+      Atv[k+1:k+s] .= transpose(ops[i]) * v
+      k += s
+    end
+    return Atv
+  end
+  function ctprod(v)
+    Atv = zeros(S, ncol)
+    k = 0
+    for i = 1:nops
+      s = size(ops[i], 2)
+      Atv[k+1:k+s] .= ops[i]' * v
+      k += s
+    end
+    return Atv
+  end
+
+  F1 = typeof(prod)
+  F2 = typeof(tprod)
+  F3 = typeof(ctprod)
+  return LinearOperator{S,F1,F2,F3}(nrow, ncol, false, false, prod, tprod, ctprod)
+end
 
 vcat(A :: AbstractLinearOperator, B :: AbstractMatrix) = vcat(A, LinearOperator(B))
 
@@ -630,10 +668,49 @@ end
 
 function vcat(ops :: OperatorOrMatrix...)
   op = ops[1]
-  for i = 2:length(ops)
-    op = [op; ops[i]]
+  nops = length(ops)
+  ncol = size(op, 2)
+  for i = 2:nops
+    size(ops[i], 2) == ncol || throw(LinearOperatorException("hcat: inconsistent row sizes"))
+  end
+  nrow = sum(size(ops[i], 1) for i = 1:nops)
+  S = promote_type([eltype(op) for op in ops]...)
+
+  function prod(v)
+    Av = zeros(S, nrow)
+    k = 0
+    for i = 1:nops
+      s = size(ops[i], 1)
+      Av[k+1:k+s] .= ops[i] * v
+      k += s
+    end
+    return Av
+  end
+  tprod = @closure v -> begin
+    Atv = zeros(S, ncol)
+    k = 0
+    for i = 1:nops
+      s = size(ops[i], 1)
+      Atv .+= transpose(ops[i]) * v[k+1:k+s]
+      k += s
+    end
+    return Atv
+  end
+  ctprod = @closure v -> begin
+    Atv = zeros(S, ncol)
+    k = 0
+    for i = 1:nops
+      s = size(ops[i], 1)
+      Atv .+= transpose(ops[i]) * v[k+1:k+s]
+      k += s
+    end
+    return Atv
   end
-  return op
+
+  F1 = typeof(prod)
+  F2 = typeof(tprod)
+  F3 = typeof(ctprod)
+  return LinearOperator{S,F1,F2,F3}(nrow, ncol, false, false, prod, tprod, ctprod)
 end
 
 # Removed by https://github.com/JuliaLang/julia/pull/24017