skip multiplying identity constop (#418)

Author: jishnub

Project.toml

@@ -1,6 +1,6 @@
 name = "ApproxFunBase"
 uuid = "fbd15aa5-315a-5a7d-a8a4-24992e37be05"
-version = "0.8.7"
+version = "0.8.8"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/Operators/banded/ConstantOperator.jl

@@ -60,9 +60,22 @@ for op in (:+,:-)
     @eval ($op)(A::ConstantOperator,B::ConstantOperator) = ConstantOperator($op(A.λ,B.λ))
 end
 
-mul_coefficients(A::ConstantOperator, b) = A.λ * b
-mul_coefficients!(A::ConstantOperator, b) = b .*= A.λ
-
+function mul_coefficients(A::ConstantOperator, b)
+    λ = A.λ
+    if isone(λ)
+        T = promote_type(typeof(λ), eltype(b))
+        convert(AbstractVector{T}, b)
+    else
+        A.λ * b
+    end
+end
+function mul_coefficients!(A::ConstantOperator, b)
+    λ = A.λ
+    if !isone(λ)
+        b .*= λ
+    end
+    return b
+end
 
 ## Basis Functional