[Maxima] Natural logarithms of large numbers

George Leeman george.leeman at sbcglobal.net
Sun Nov 30 09:51:27 CST 2008


Weaker, you're correct.  The expression 'bfloat(log(10^400));' works fine.
Thanks for your help.
-- George Leeman 
---------------------------------------------------------------------
-----Original Message-----
From: weaker [mailto:weaker at directbox.com] 
Sent: Sunday, November 30, 2008 10:21 AM
To: George Leeman
Cc: maxima at math.utexas.edu
Subject: Re: [Maxima] Natural logarithms of large numbers

1.7976931348623157e+308 is the limit of the normal double floating
point arithmetic. That's probably the reason and it is not an
arbitrary limit that can be changed easily. Perhaps you need to use
bfloats but I'm no Maxima expert.
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-----Original Message-----
From: George Leeman [mailto:george.leeman at sbcglobal.net] 
Sent: Sunday, November 30, 2008 9:40 AM
To: maxima at math.utexas.edu
Subject: Natural logarithms of large numbers

In wxMaxima 0.7.6 + Maxima 5.16.3 I get the following sequence:

  (%i1) log(10^308), numer;
  (%o1) 709.1962086421661
  (%i2) log(10^309), numer;
  Maxima encountered a Lisp error:
   Error in SETQ [or a callee]: Can't print a non-number.
  Automatically continuing.
  To reenable the Lisp debugger set *debugger-hook* to nil.
  (%i3) log(10^308)+log(10), numer;
  (%o3) 711.4987937351601
  (%i4)  

Have I reached some strange boundary here?  Is there a way to move the
boundary upward (say to 10^400) instead of breaking the calculation into
pieces?  
-- George Leeman




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