I was just throwing in a value to stop a calculation if the result is under that value, I could as well choose 2^16, it just happened to be 2^32.
On Sunday, January 12, 2014 5:50:23 PM UTC+1, Alessandro Andrioni wrote: > > In this case, you just need either one of the values converted to a > BigInt, and big(2)^32 is marginally more efficient than 2^big(32), > since it allocates one less BigInt. > > Also, wouldn't typemax(Int)/typemax(Uint) be what you want here? > > On 12 January 2014 14:29, Ivar Nesje <[email protected] <javascript:>> > wrote: > > I really agree that this is a mistake that is easily made. There is a > FAQ > > answer that explains why we use integer arithmetic with silent overflow. > > > > I think Julia would benefit from a simpler way to express numerical > > constants with type than to first create a Float64 / Int32/64 and then > send > > to constructor, but I have not (yet) found a syntax to suggest that > would > > get approval. > > > > One idea might be to implement a @big macro that would allow you to > write > > @big(2^32) > > and it would be automatically translated to > > big(2)^big(32) > > > > The problem is that it will not work (in a sensible way) for floating > point, > > because the macro will not be able to see the string representation, but > the > > closest Float64 version. This means that 0.1 will be > > 1.000000000000000055511151231257827021181583404541015625e-01 instead of > > > 1.000000000000000000000000000000000000000000000000000000000000000000000000000002e-01 > > > > > > kl. 17:02:25 UTC+1 søndag 12. januar 2014 skrev Földes László følgende: > >> > >> This little piece of code tricked me: > >> > >> if value < big(2^32) > >> println("Finished!") > >> break > >> end > >> > >> The println was never executed and couldn't find the problem for about > 3 > >> minutes when I tried it on a 64 bit OS, where it worked. > >> The problem is that on 32-bit OS 2^32 equals to zero. I'm just getting > >> used to Julia internals and it is not really a problem if it is > apparent, > >> but I clearly need more time with the language to spot these kind of > error. > >> > >> if value < big(2)^big(32) > >> println("Finished!") > >> break > >> end > >> solve this. But this is ugly and it looks like something that can be > >> automated. > >> > >> is there any coding style that can prevent this error? I would better > >> receive an overflow error (if it is turned on with a flag to the Julia > >> executable maybe) than a silent, never running piece of code. >
