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Re: TPR1 post-mortem
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From:
Marcelo E. Magallon
Date:
March 8, 2002 06:22
Subject:
Re: TPR1 post-mortem
Message ID:
20020308141610.GA30975@informatik.uni-stuttgart.de
>> Jason Purdy <jason@journalistic.com> writes:
> Is that #*1.11%10 a number theory to get to the same number? How did
> someone recognize that pattern? (my advanced calculus/comb math being
> a lil' rusty)
I don't know others, but I started by looking at the input and output,
like this:
0 0
1 1
... ...
9 9
10 1
11 2
12 3
... ...
18 9
19 1
20 2
As you can see it's just a series of 1 .. 9, except for 0. With that
in mind my first I tried something like (0,(1..9)x11)[$n]. Actually,
before that I tried something more like (0,(1..9)x2)[$a+$b] (where $a
and $b are the digits). Then I noticed that I could get the same
result using %9 and some conditionals. After putting this stuff aside
and having some sleep I just pictured the thing as a table like this:
0 1 2 3 4 ...
0 00 11 22 33 44 ...
1 10 21 32 43 54 ...
...
8 80 91 12 23 34 ...
9 90 11 22 33 44 ...
which made it kind of evident that 111%100 should do what I wanted.
*Then* I had a different problem to solve :-)
> What is \G ... $&? Gotta dig out my Camel book again.
Check out perlre and perlvar and the "g" option to m//.
A question of my own: why doesn't
s/\B.\B/$&$&/g
work as I expect, namely abcd -> abbccd. I really can't figure it out
by reading the docs.
TIA,
Marcelo
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