Repeatative piping

[abreauj-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org (John Abreau)]

Bash has the traditional C-style for-loop in addition to the classic
Bourne-style for-loop.

    for i in a b c d e f g ; do echo $i ; done

    for (( i=0 ; i < 10 ; i++ )) ; do echo $i ; done

So you could probably do something like

    FOO=$(g_u1 1 2 3 4)
    for (( i=0 ; i < 1000 ; i++ )) ; do
        FOO=$(echo $FOO | q_square)
    done
    echo $FOO



On Sun, Feb 22, 2009 at 12:11 PM, Doug <dougsweetser-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:
> Hello:
>
> Just sitting around the house on a Sunday, trying to create the group
> U(1), a group involved with light.  I wrote a program that does one of
> the steps:
>
>> g_u1 1 2 3 4
> 0.1825741858350554 0.3651483716701107 0.5477225575051661 0.7302967433402214
>
> That is a normalized quaternion.  To make more members of the group,
> square the result:
>
>> g_u1 1 2 3 4 | q_square
> -0.933333 0.133333 0.200000 0.266667
>
> I'd like to do this a thousand times:
>
>> g_u1 1 2 3 4 | q_square | q_square | q_square ...
>
> There are lots of ways to do this.  One easy approach for me is write
> q_square_n, that given an n, does the loop.  I was curious if there
> was command line way to accomplish the same thing.  I don't know if I
> have used a for loop in a command line setting before.
>
> Doug
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>



-- 
John Abreau / Executive Director, Boston Linux & Unix
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