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. >
See http://trac.sagemath.org/sage_trac/ticket/7830 for a patch for the following functionality: sage: R=RealField(53) sage: a=R(exp(1.0)); a 2.71828182845905 sage: sign,mantissa,exponent=R(exp(1.0)).representation() sage: sign,mantissa,exponent (1, 6121026514868073, -51) sage: sign*mantissa*(2**exponent)==a True I'm not happy with the name ("representation"). What do people think? Thanks, Jason -- 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
