Merge branch 'master' into isconcrete

Author: vpuri3

src/interface.jl

@@ -453,6 +453,15 @@ for op in (
     end
 end
 
+for op in (
+           :sum, :prod,
+          )
+    @eval function Base.$op(L::AbstractSciMLOperator; kwargs...)
+        @warn """using convert-based fallback in $($op)."""
+        $op(convert(AbstractMatrix, L); kwargs...)
+    end
+end
+
 for pred in (
              :issymmetric,
              :ishermitian,