directly compute element type when possible

Author: rdeits

src/b-splines/b-splines.jl

@@ -25,8 +25,11 @@ function BSplineInterpolation(::Type{TWeights}, A::AbstractArray{Tel,N}, ::IT, :
     for _ in 2:N
         c *= c
     end
-    T = Base.promote_op(*, typeof(c), Tel)
-
+    if isempty(A)
+        T = Base.promote_op(*, typeof(c), Tel)
+    else
+        T = typeof(c*first(A))
+    end
     BSplineInterpolation{T,N,typeof(A),IT,GT,pad}(A)
 end
 

src/gridded/gridded.jl

@@ -28,8 +28,11 @@ function GriddedInterpolation(::Type{TWeights}, knots::NTuple{N,GridIndex}, A::A
     for _ in 2:N
         c *= c
     end
-    T = Base.promote_op(*, typeof(c), TCoefs)
-
+    if isempty(A)
+        T = Base.promote_op(*, typeof(c), Tel)
+    else
+        T = typeof(c*first(A))
+    end
     GriddedInterpolation{T,N,TCoefs,IT,typeof(knts),pad}(knts, A)
 end