logarthim
Paul Leyland
pleyland@microsoft.com
Mon, 28 Oct 2002 05:07:30 -0800
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Three answers:
=20
1) The log is (generally) not an integer.
2) Log(0) is undefined
2) If you want floor(log(N)), for N>1, the function to use is =
mpz_sizeinbase()
=20
The rest you can look up in the manual.
=20
Extending the function to N<0 or N=3D1, and determining the fractional =
part is left as an exercise.
=20
=20
Paul
=20
-----Original Message-----
From: Jan Sahner [mailto:jan@quaeldich.de]=20
Sent: 28 October 2002 12:22
To: Hatem Bahig
Cc: gmp-discuss@swox.com
Subject: Re: logarthim
=09
=09
I don't think that this is conceptually possible, as this should =
usually be an irrational number.=20
Yours,=20
Jan=20
Hatem Bahig wrote:=20
Dear all I would be thankful if some one inform me the name of =
function to calculate the logarithm (log to base 2) for any integer =
(mpz) (in GMP)? Thank you in advance.=20
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<BODY bgColor=3D#ffffff>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2>Three=20
answers:</FONT></SPAN></DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2>1) The=20
log is (generally) not an integer.</FONT></SPAN></DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2>2)=20
Log(0) is undefined</FONT></SPAN></DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2>2) If=20
you want floor(log(N)), for N>1, the function to use is=20
mpz_sizeinbase()</FONT></SPAN></DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2>The=20
rest you can look up in the manual.</FONT></SPAN></DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2>Extending the function to N<0 or N=3D1, and determining the =
fractional=20
part is left as an exercise.</FONT></SPAN></DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3D075545912-28102002></SPAN><SPAN =
class=3D075545912-28102002><FONT=20
face=3DArial color=3D#0000ff size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2>Paul</FONT></SPAN></DIV>
<DIV><SPAN class=3D075545912-28102002><FONT face=3DArial color=3D#0000ff =
size=3D2></FONT></SPAN> </DIV>
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<DIV class=3DOutlookMessageHeader lang=3Den-us dir=3Dltr =
align=3Dleft><FONT=20
face=3DTahoma size=3D2>-----Original Message-----<BR><B>From:</B> Jan =
Sahner=20
[mailto:jan@quaeldich.de] <BR><B>Sent:</B> 28 October 2002 =
12:22<BR><B>To:</B>=20
Hatem Bahig<BR><B>Cc:</B> gmp-discuss@swox.com<BR><B>Subject:</B> Re:=20
logarthim<BR><BR></FONT></DIV>I don't think that this is conceptually=20
possible, as this should usually be an irrational number. <BR>Yours, =
<BR>Jan=20
<BR>Hatem Bahig wrote:=20
<BLOCKQUOTE TYPE=3D"CITE">
<STYLE></STYLE>
<FONT face=3DArial><FONT size=3D-1>Dear all</FONT></FONT> <FONT =
face=3DArial><FONT size=3D-1> I would be thankful if some one =
inform me the=20
name of function to calculate the logarithm (log to base 2) =
for any=20
integer (mpz) (in GMP)?</FONT></FONT> <FONT face=3DArial><FONT=20
size=3D-1>Thank you in=20
advance.</FONT></FONT> </BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>
=00
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