I have recently become aware of Julia and have been impressed with its ease of use and speed. While I was converting my previous code to Julia, I noticed that trigonometric functions at infinity yield DomainError and abort the program. Try sin(Inf), sin(-Inf), cos(Inf), tan(Inf), etc. I checked the behavior of Numpy and it returns a NaN and a warning of invalid value to the function. I remember Matlab was yielding a NaN too. But they both wouldn't abort the program.
Returning a NaN instead of aborting the program might be useful when the following computations don't depend on only this result of NaN. For example, consider finding the smallest element of x =cos( [1.0, 2.0, Inf]) which would have given the number I am interested in if cos(Inf) gives a NaN. Here I cos(2.0) < NaN would be false nevertheless findmin cleverly finds the correct answer 2.0 ( so does Numpy). Note that Inf is usually a result of an intermediate step of an algorithm. If the following computations involve NaN and yield compilation error than checking elements of x being not NaN is necessary. But since it does occur rarely, avoiding this check might be useful for speed. What would be your thoughts? Thanks.
