2010/1/3 Jason Grout <jason-s...@creativetrax.com>: > Dr. David Kirkby wrote: >> The IEEE 754 representation of a floating point number is basically >> >> (-1)^2 x c x 2^q >> s=sign bit >> c=significand (or 'coefficient') >> q=exponent >> >> http://en.wikipedia.org/wiki/IEEE_754-2008 >> >> E is most accurately represented by: >> >> 6121026514868073 x 2^-51 >> >> though on my SPARC the best one gets is >> >> 6121026514868074 x 2^-51 >> >> I wanted to know how to convert a floating point number to that format using >> Mathematica. The very knowledgeable and helpful Daniel Lichtblau of Wolfram >> Research answered my question on sci.math.symbolic. I must admit I was >> impressed >> how few lines of code it took him. >> >> $ cat RealToIEEE754.m >> >> RealToIEEE754[x_]:=Block[{s,digits,expon,c,q}, >> s=Sign[x]; >> {digits,expon}=RealDigits[x,2]; >> c = FromDigits[digits, 2] ; >> q = expon - Length[digits] ; >> {s,c,q} ] >> >> >> In[1]:= <<RealToIEEE754.m >> >> In[2]:= RealToIEEE754[Exp[1.]] >> >> Out[2]= {1, 6121026514868074, -51} >> >> >> I was wondering how elegant one could implement that in Sage. >> > > Here's yet another way to do it: > > sage: import mpmath > sage: b=mpmath.mpf(exp(1.0)) > sage: b > mpf('2.7182818284590451') > sage: b.man # mantissa > 6121026514868073 > sage: b.exp # exponent > -51 > > Thanks, > > Jason
OK, Mathematica is no shorter than Sage in this respect. dave -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
