Re: [ferret_users] ceil, floor, and round

[Ge Peng <gpeng@xxxxxxxxxxxxxxxxxxxxxxx>]

Ryo and Andrew:

Thanks for your reply.  I have tried Andrew's solution and it works fine
for me.

Thanks,

--- Peng

> let floor_a = int(a) - (a LT 0 AND int(a) NE a)
> let ceil_a  = int(a) + (a GT 0 AND int(a) NE a)
> let round_a = int(a-.5+(a GE 0))
>
> Andrew
>
> On Tue, 29 Sep 2009, Ryo Furue wrote:
>
>> Hi Peng,
>>
>> | Does ferret have functions similar to ceil, floor, round in matlab
>> (please
>> | see their definitions below)?
>>
>> I don't know the official answer, but I guess Ferret doesn't have those
>> functions built in.  In case it doesn't, I give some ideas on how to
>> define them.
>>
>> | CEIL(X) rounds the elements of X to the nearest integers towards
>> infinity.
>> | FLOOR(X) rounds the elements of X to the nearest integers towards
>> minus
>> | infinity.
>> | ROUND(X) rounds the elements of X to the nearest integers.
>>
>> You can construct them from the "int()" function, which Ferret does
>> have.
>>
>> INT is the same as FLOOR for positive arguments but it truncates
>> toward zero instead of toward minus infinity:
>>
>>  INT(1.4)  == 1
>>  INT(-1.4) == -1
>>
>> So,
>>
>>  FLOOR(a)
>>   = if (a is a whole number)
>>     then a
>>     else if (a < 0)
>>          then INT(a) - 1
>>          else INT(a)
>>
>> In Ferret statements,
>>
>>  let int_a = int(a)
>>  let floor_a = if int_a eq a then a else floor_a_helper
>>  let floor_a_helper = if a lt 0 then int_a - 1 else int_a
>>
>> Likewise,
>>
>>  ROUND(a)
>>   = if (a is a whole number)
>>     then a
>>     else if (a < 0)
>>          then INT(a - 0.5)
>>          else INT(a + 0.5)
>>
>> These formulae are rather tedious.  There may be better
>> definitions.
>>
>> Regards,
>> Ryo
>>
>