20111102, 01:24  #1 
6809 > 6502
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Aug 2003
101×103 Posts
24434_{8} Posts 
James H's http://mersennearies.sili.net utility site.
I could not find a good simple thread for this.
I think that maybe we should have a subforum someplace for the handy sites like this and mersenne.info and Dario's ECM applet. I found and error in the calculations on this page: http://mersennearies.sili.net/exponent.php Code:
echo '<div>has '.number_format(ceil($_REQUEST['exponentdetails'] * log(2))).' decimal digits</div>'; Code:
echo '<div>has '.number_format(ceil($_REQUEST['exponentdetails'] * log(2) / ln(10) )).' decimal digits</div>'; This page: http://mersennearies.sili.net/digits.php does the calculation correctly. HTH 
20111102, 10:32  #2 
Jun 2003
5360_{10} Posts 
if a language has both log and ln, then first one will be base10 log and second one will be natural log. In which case, log(2) is sufficient. OTOH, may be you typoed and meant log(2) / log(10)?

20111102, 12:36  #3  
6809 > 6502
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Aug 2003
101×103 Posts
2^{2}×3×877 Posts 
Quote:
Code:
<script type="text/javascript"> function DigitsExp() { document.getElementById('digits_text_input').value = Math.ceil(document.getElementById('exponent_text_input').value * (Math.log(2) / Math.LN10)); // log(2, 10) = 0.301029995664 } function ExpDigits() { document.getElementById('exponent_text_input').value = Math.floor(document.getElementById('digits_text_input').value / (Math.log(2) / Math.LN10)); // log(2, 10) = 0.301029995664 } </script> 

20111102, 13:36  #4  
Jun 2003
2^{4}×5×67 Posts 
Quote:
EDIT: I am, of course, talking about "echo '<div>has '.number_format(ceil($_REQUEST['exponentdetails'] * log(2) / ln(10) )).' decimal digits</div>';" thing. EDIT2: PHP log function takes an optional base argument, so log(2, 10) would be the way to go. EDIT3: Or better yet, use log10(2) Last fiddled with by axn on 20111102 at 13:45 

20111102, 13:40  #5  
"Forget I exist"
Jul 2009
Dumbassville
2^{6}×131 Posts 
Quote:


20120811, 01:20  #6 
6809 > 6502
"""""""""""""""""""
Aug 2003
101×103 Posts
2^{2}×3×877 Posts 
I saw Chalsall's post over here: http://mersenneforum.org/showthread.php?t=17049
So, I decide to go over and submit all of the results I had lying around. It does not give credit for factors it already knows about. And I broke the website. I submitted this Factor5 result: Code:
Trialfactoring M11111111111111111111111 in [2^1, 2^1001] M11111111111111111111111 has a factor: 5246666666666666666666614201  Program: L5.0x M11111111111111111111111 has 1 factors in [2^1, 2^1001]. 
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