Merge pull request #174 from vpuri3/compose_cache

clean up caching for composeoperator

Author: xtalax

src/basic.jl

@@ -578,32 +578,24 @@ function Base.:*(L::ComposedOperator, u::AbstractVecOrMat)
 end
 
 function cache_self(L::ComposedOperator, u::AbstractVecOrMat)
-    if has_mul(L)
-        vec = zero(u)
-        cache = (vec,)
-        for i in reverse(2:length(L.ops))
-            vec   = L.ops[i] * vec
-            cache = (vec, cache...)
-        end
-    elseif has_ldiv(L)
-        m = size(L, 1)
-        k = size(u, 2)
-        vec = u isa AbstractMatrix ? similar(u, (m, k)) : similar(u, (m,))
-        cache = ()
-        for i in 1:length(L.ops)
-            vec   = L.ops[i] \ vec
-            cache = (cache..., vec)
-        end
-    else
-        error("ComposedOperator cannot be cached without supporting either mul or ldiv.")
+
+    K = size(u, 2)
+    cache = (zero(u),)
+    for i in reverse(2:length(L.ops))
+
+        M = size(L.ops[i], 1)
+        T = promote_type(eltype.((L.ops[i], cache[1]))...)
+        sz = u isa AbstractMatrix ? (M, K) : (M,)
+
+        cache = (similar(u, T, sz), cache...)
     end
 
     @set! L.cache = cache
     L
 end
 
 function cache_internals(L::ComposedOperator, u::AbstractVecOrMat)
-    if !iscached(L)
+    if isnothing(L.cache)
         L = cache_self(L, u)
     end