unwrap hvcat in Fourier multiplication (#73)

Author: jishnub

src/FourierOperators.jl

@@ -274,8 +274,11 @@ rangespace(M::ConcreteMultiplication{Cs,SS}) where {SS<:SinSpace,Cs<:CosSpace} =
 function Multiplication(a::Fun{Fourier{D,R},T},sp::Fourier{D,R}) where {T,D,R}
     d=domain(a)
     c,s=components(a)
-    O=Operator{float(T)}[Multiplication(c,CosSpace(d)) Multiplication(s,SinSpace(d));
-                        Multiplication(s,CosSpace(d)) Multiplication(c,SinSpace(d))]
+    O = Matrix{Operator{float(T)}}(undef, 2, 2)
+    O[1,1] = Multiplication(c,CosSpace(d))
+    O[2,1] = Multiplication(s,CosSpace(d))
+    O[1,2] = Multiplication(s,SinSpace(d))
+    O[2,2] = Multiplication(c,SinSpace(d))
     MultiplicationWrapper(a,InterlaceOperator(O,space(a),sp))
 end