[Tutor] Re: rotating a list

[Bob Gailer]

At 02:33 PM 9/20/2003, Andrei wrote:

>Bob Gailer wrote:
>>>Here's your problem your rotate x and assign the result to y:
>>>
>>>>         y = rotate(x)
>>>
>>>
>>>Now x is unchanged, y is the result, so you go back and rotate the same 
>>>old x again. Obviously the result won't change.
>>>
>>>>         print y
>>
>>No that is NOT the problem. That is an alternative algorithm. I explained 
>>the problem in my post.
>
>As far as I can tell, that's a matter of taste: the algorithm is exactly 
>the same and the result is the same: he uses the default value of n=1 in 
>this case to test his rotation which is just fine. One can either 
>increment n in the loop or reassign x every time. Personally, I find 
>reassigning more intuitive and I pretty much ignored the optional n 
>parameter. Could you explain why incrementing n is a superior solution?

I guess I overreacted in my reply. I did see what you saw first, then when 
I tested the code and saw the missing parameter I assumed the OP meant to 
provide it. Sorry for the reaction.

As a (mostly former) APL programmer I still like APL's approach best:

n$matrix

where $ is replaced by the non-ascii symbol for rotate.

Bob Gailer
bgailer at alum.rpi.edu
303 442 2625
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