Mismatch between input datatype and interpolated type for `Float32`

[hzarei4]

Suppose you have an array of

a = rand(Float32, (10, 11))

As you have mentioned in this commit, the eltype of the interpolate object

itp = interpolate(a, BSpline(Linear()))

is Float32. Then we want to calculate the value of

julia> typeof(itp(1.1, 1.1))
Float64

Then, interestingly

julia> typeof(itp(1.1f0, 1.1f0))
Float32

I think this is an issue with handling the datatypes. I suggest that the interpolation output type should be the input data a we feed the function with, NOT the input type of the itp.

[mkitti]

Thanks. That seems reasonable. Could you make a pull request?