[Fwd: Re: [Tutor] how to write an algorithm for sequence]
reavey
reavey@nep.net
Tue Feb 11 22:36:15 2003
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-------- Original Message --------
Subject: Re: [Tutor] how to write an algorithm for sequence
Date: Wed, 12 Feb 2003 22:28:08 -0500
From: reavey <reavey@nep.net>
To: Danny Yoo <dyoo@hkn.eecs.berkeley.edu>
References:
<Pine.LNX.4.44.0302111904390.28496-100000@hkn.eecs.berkeley.edu>
Yes. I wrote this as a power of two sequence. I can see how to get the
next number, however
the algorithm is baffling.
Thanks
re-v
Danny Yoo wrote:
>On Wed, 12 Feb 2003, reavey wrote:
>
>
>
>>I'm stumped. I made up this sequence and I can't figure out a method.
>>the sequence is 1,5,7,15,19,35, 43, 75...
>>
>>
>
>Hi Reavey,
>
>
>This isn't quite Python either, but I'll give it a shot. *grin*
>
>Hmmm... I don't see anything immediate from the sequence above either.
>
>
>But have you tried the method of differences? Here's how it works: take
>each pair of numbers, subtract them, and see if a pattern emerges.
>
>###
>
>
>>>>def differences(seq):
>>>>
>>>>
>... for i in range(0, len(seq)-1):
>... print seq[i+1] - seq[i],
>...
>
>
>>>>differences([1, 5, 7, 15, 19, 35, 43, 75])
>>>>
>>>>
>4 2 8 4 16 8 32
>###
>
>
>Let's arrange it so that it's easier to see what's going on:
>
>
> 1 5 7 15 19 35 43 75
> 4 2 8 4 16 8 32
>
>
>
>Interesting. All of the individual "differences" are even, first of all.
>Wait: Reavey, I do see some sort of pattern here. Do you see it too now?
>
>
>
>Good luck to you!
>
>
>
>
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<th valign="baseline" align="right" nowrap="nowrap">Subject: </th>
<td>Re: [Tutor] how to write an algorithm for sequence</td>
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<td>Wed, 12 Feb 2003 22:28:08 -0500</td>
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<th valign="baseline" align="right" nowrap="nowrap">From: </th>
<td>reavey <a class="moz-txt-link-rfc2396E" href="mailto:reavey@nep.net"><reavey@nep.net></a></td>
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<td>Danny Yoo <a class="moz-txt-link-rfc2396E" href="mailto:dyoo@hkn.eecs.berkeley.edu"><dyoo@hkn.eecs.berkeley.edu></a></td>
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<td><a class="moz-txt-link-rfc2396E" href="mailto:Pine.LNX.4.44.0302111904390.28496-100000@hkn.eecs.berkeley.edu"><Pine.LNX.4.44.0302111904390.28496-100000@hkn.eecs.berkeley.edu></a></td>
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Yes. I wrote this as a power of two sequence. I can see how to get
the next number, however<br>
the algorithm is baffling.<br>
Thanks<br>
re-v<br>
<br>
Danny Yoo wrote:<br>
<blockquote type="cite"
cite="midPine.LNX.4.44.0302111904390.28496-100000@hkn.eecs.berkeley.edu">
<pre wrap="">On Wed, 12 Feb 2003, reavey wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I'm stumped. I made up this sequence and I can't figure out a method.
the sequence is 1,5,7,15,19,35, 43, 75...
</pre>
</blockquote>
<pre wrap=""><!---->
Hi Reavey,
This isn't quite Python either, but I'll give it a shot. *grin*
Hmmm... I don't see anything immediate from the sequence above either.
But have you tried the method of differences? Here's how it works: take
each pair of numbers, subtract them, and see if a pattern emerges.
###
</pre>
<blockquote type="cite">
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">def differences(seq):
</pre>
</blockquote>
</blockquote>
</blockquote>
<pre wrap=""><!---->... for i in range(0, len(seq)-1):
... print seq[i+1] - seq[i],
...
</pre>
<blockquote type="cite">
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">differences([1, 5, 7, 15, 19, 35, 43, 75])
</pre>
</blockquote>
</blockquote>
</blockquote>
<pre wrap=""><!---->4 2 8 4 16 8 32
###
Let's arrange it so that it's easier to see what's going on:
1 5 7 15 19 35 43 75
4 2 8 4 16 8 32
Interesting. All of the individual "differences" are even, first of all.
Wait: Reavey, I do see some sort of pattern here. Do you see it too now?
Good luck to you!
</pre>
</blockquote>
<br>
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