Ben Schmidt wrote:
>> When would you need Float -> Int? You can actually use
>> printf(".0f", float), and rely on automatic String to Int conversion,
>> but it's clumsy.
>
> Float -> Int can be very handy, using floats as intermediate
> calculations in scripts and then converting to ints for some kind of
> display or condition, but usually in combination with a well-defined way
> of converting between...i.e. a ceil, floor, round function. It would be
> good if some of these could be implemented. How about a single round
> function with a second parameter to specify the type of rounding, and
> return an int? The second argument could be 'floor|down|int' (round
> down), 'ceil|up' (round up), 'trunc|zero' (towards zero), 'away' (away
> from zero), 'nearest|round' (towards nearest integer, round away from
> zero if half way), 'even' (towards nearest integer, round to the even
> number if half way).
>
>>> 2. This is not strictly related to floating point, just noticed:
>>>
>>> :echo 1/0
>>> 2147483647
>>>
>>> :echo 1.0/0
>>> 2.147484e+09
>>>
>>> Shouldn't divide by 0 throw error?
>> The number you see is the largest int value or a special value for
>> floats which is INFINITY.
>
> Something is wrong there, because it's not anywhere near the largest
> value for floats, it is simply the largest value for a 32 bit int
> converted to a float. Looks like some integer code has interfered with
> the float code. Only on your system though. My system correctly reports
> 'inf', the special IEEE floating point representation of 'infinity'.
>
> There is still a bug there, though:
>
> :echo -1/0 " gives 2147483647, see below
> :echo 0/0 " gives 2147483647, see below
> :echo -1.0/0 " gives inf, should give -inf
> :echo 0.0/0 " gives inf, should give nan
It may also be worth noting that 0.0 and -0.0 are (or should be)
different floats, so, for instance 1/-0.0 should give -inf.
> For the integer ones, the negative should report, if the 'maximum value'
> philosophy is followed, -2147483648 (==-2^31, the smallest value a
> 32-bit int can represent). Though in Vim, a case could be made for
> actually returning -2147483647 (i.e. one unit 'too high') since in Vim
> -(-2147483648) == -2147483648 due to overflow, which isn't very
> desirable! In practice, using -2147483647 and having a sign change work
> as expected would be more useful. Care would have to be taken to have
> things that work on 64 bit systems, too, I guess (and systems with
> smaller words if we still compile for those!). However, this whole idea
> isn't all that useful with ints anyway. It is useful with floats,
> though, In most environments, integer division by zero chucks an error
> and float division reports inf, -inf or nan as appropriate.
>
> Apart from various types rounding, which I can definitely imagine being
> useful, are there any mathematical functions that could be handy in a
> text processing environment? So far I can only think of 'toy'
> applications for them! Perhaps to minimise disruption but allow
> flexibility they could all be wrapped in a 'math' function, where the
> first argument is the function, and the second and optionally third
> arguments are the parameters?
>
> math('sqrt',argument)
> math('exp',exponent[,base=e])
> math('log',argument[,base=e])
> math('sin',argument[,degrees (bool)=0])
> math('cos',argument[,degrees (bool)=0])
> math('tan',argument[,degrees (bool)=0])
> math('atan',argument[,degrees (bool)=0])
>
> I think that covers all the basics in an extensible and inobtrusive way.
>
>>> 4. Cosmetic thing but truncating of 0s in floating numbers would be user
>>> friendly (eg. store and display 0.5 instead of 0.500000)
>> I don't see an argument to printf() to get this.
>
> Yeah, that'd be a good improvement.
>
> Are floats or doubles being used? They are definitely being displayed
> with float, not double, precision at present. I would vastly prefer
> double precision. 7 significant figures is barely worth it, and wouldn't
> cut it for a lot of data files where having floating points in a text
> editor would actually be useful! 15 significant figures gives you a lot
> of power, and would allow you to interact with the floating points just
> as accurately as most other software that would be reading your data
> files.
>
> Ben.
>
>
>
> >
>
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