Re: Can Bash do simple math?

[alex xmb sw ratchev]

i missed a few question marks .. sorry ..

On Tue, Aug 6, 2024, 17:08 alex xmb sw ratchev <fxmbsw7@gmail.com> wrote:

> ah its like array matching .. uh i had nice awk script , ill make new ..
>
> so the % 60 or so code is * 60 ..
> weird
>
> a number , big , prolly smaller than bash max ?
> then thats already seconds
>
> it implents a ' pseudo 60 ' case
> where in end to * 60
>
> i really dont see why 60
>
> about my awk , ill do a math converter
> like 123456 is 123t456
> i mean convert numbers to multi-stuffix human-readable form
>
> On Tue, Aug 6, 2024, 16:47 Greg Wooledge <greg@wooledge.org> wrote:
>
>> On Tue, Aug 06, 2024 at 16:35:39 +0200, alex xmb sw ratchev wrote:
>> > On Tue, Aug 6, 2024, 00:34 <bash@blaklinten.xyz> wrote:
>> >
>> > > I have a somewhat strange issue.
>> > > In a script I use the `((VAR = expression ))` syntax to calculate a
>> > > simple remainder by division:
>> > >
>> > >   ((DIFF = $2 - $1))
>> > >   ((SECONDS = DIFF % 60))
>> > >   ((MINUTES = (DIFF % 3600) / 60))
>> > >   ((HOURS = DIFF / 3600))
>> > >
>> >
>> > just .. what u do diff % 60 , 'SECONDS' it is already .. % 60 ( if it
>> > counts as how many 60thiet times ) is minutes already
>> > i suppose u mean $2(seconds) -1(seconds) , = seconds
>> > if thats not ur case plz explain
>>
>> The code is converting a (large) number of seconds into a time interval
>> expressed as a number of hours, plus a number of minutes, plus a number
>> of seconds.
>>
>> There are a few different ways to perform this calculation.  The most
>> straightforward IMHO would be:
>>
>>  1) Divide the total by 3600 to get the number of hours.
>>  2) Decrease the total by (3600*hours).
>>  3) Divide the new total by 60 to get the number of minutes.
>>  4) Decrease the total by (60*minutes).
>>  5) The remaining total is the number of seconds.
>>
>> The poster is using a slight variant, in which the number of hours and
>> the number of seconds are calculated directly from the total, and the
>> number of minutes is calculated directly from the total in two steps,
>> without modifying the total or introducing an explicit temporary variable.
>>
>>  1) The number of seconds is the total mod 60.
>>  2) The number of hours is the total divided by 3600.
>>  3) The number of minutes is computed by first taking the total mod 3600
>>     (which removes the whole hours), and then dividing that by 60.
>>
>> There is an *implicit* temporary variable in step 3, but it's not given
>> a name or a formal storage allocation.
>>
>>