On Thu, Apr 24, 2014 at 4:28 AM, Hans W Borchers <[email protected]>wrote:
>
> function trapz2{T<:Number}(x::Vector{T}, y::Vector{T})
> local n = length(x)
> if (length(y) != n)
> error("Vectors 'x', 'y' must be of same length")
> end
> if n == 1; return 0.0; end
> r = 0.0
> for i in 2:n
> r += (x[i] - x[i-1]) * (y[i] + y[i-1])
>
> end
> r / 2.0
> end
>
>
I'm not sure it's behavior we should "rely on", but the if branch for n ==
1 isn't necessary in this for loop, although perhaps it was included to aid
the comparison. A range of 2:1 is a zero-length iteration, so the loop will
not run even once. Try this:
julia> [2:1]
0-element Array{Int64,1}
If we are being pedantic on types, then the result of the integral should
at least be a floating point. Granted, I am not sure of what the use case
for integer vector inputs would be, but I doubt *if* someone used them that
they'd want an integer result in return. (This would be similar to sqrt(),
for example.)
Cameron
