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Subject: Re: why do ceil/floor give the decimal dot?
From: =?utf-8?Q?Lawrence_Vel=C3=A1zquez?= <vq@larryv.me>
In-Reply-To: <87d223et0a.fsf@debian.uxu>
Date: Wed, 13 May 2015 23:53:53 -0400
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References: <87oalodmns.fsf@debian.uxu> <150513195617.ZM29493@torch.brasslantern.com> <87d223et0a.fsf@debian.uxu>
To: Emanuel Berg <embe8573@student.uu.se>
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On May 13, 2015, at 11:29 PM, Emanuel Berg <embe8573@student.uu.se> wrote:

> Take a look at this [1] zsh:
> 
>    prefix-len () {
>        local hosts=$1
>        echo $(( 32 - int(ceil(log($hosts)/log(2))) ))
>    }
> 
> without the integer conversion, the output for
> 
>    prefix-len 30
> 
> isn't 27, but "27."

Yes, this is expected and correct. From "ARITHMETIC EVALUATION" in the
zshmisc(1) man page:

    Promotion of integer to floating point values is performed where
    necessary.

So:

- "ceil(log(30)/log(2))" returns floating-point "5."
- integer "32" is promoted to floating point "32."
- floating point "32." - floating point "5." = floating-point "27."

vq