Re: [PLUG] floor/ceil in bash?

[Jason Stelzer <jason.stelzer@gmail.com>]

Well, to be fair....

First, thanks, that's a good idea. I'll just do that.

Second, I really just need to always round up the the nearest whole number.

On Wed, Sep 16, 2009 at 7:33 PM, Paul L. Snyder <plsnyder@drexel.edu> wrote:
> On Wed, September 16, 2009, Jason Stelzer"  wrote:
>
>> The details are boring and irritating, but I'm looking to get the ceil
>> for something in bash. Here's how I'm brute forcing it.
> [...]
>> Is there an easier way? And yeah, I know that using _MY_CEIL as a
>> bucket is kind of weird. Either way the code looks odd to me.
>
> Bash does not support floating-point math, unless they've done something
> sneaky in recent releases that I don't know about.  Trying to make it
> do so on your own will only lead to woe.  I haven't traced through your
> script, but I'd be pretty suspicious of it.
>
> If you don't want to use a shell that supports floating-point math
> (such as zsh), I'd recommend turning to bc at a time like this.
>
> First define a bash function that calls bc.  In bc, "scale" is the number of
> positions after the decimal place that are retained after some arithmetic
> operations.  By default, scale is 0, so dividing by 1 returns the integer
> portion of a number.  The $1 is the first argument to the bash ceil function
> being defined.
>
> ------
> function ceil () {
>  echo "define ceil (x) {if (x<0) {return x/1} \
>         else {if (scale(x)==0) {return x} \
>         else {return x/1 + 1 }}} ; ceil($1)" | bc;
> }
> ------
>
> To stuff a value into an envar, call with command substitution:
>
>  $ X=5.5
>  $ CEIL_X=$(ceil x)
>  $ echo $CEIL_X
>  6
>
> HTH,
> Paul
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-- 
J.
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