[Coco] printing out floating point numbers...(only peripherally related to coco)

[jdaggett at gate.net]

On 14 Jul 2006 at 16:42, Robert Gault wrote:

> jdaggett at gate.net wrote:
> > Robert
> > 
> > Someth9ing jgged the memory when y ou mentioned Fractals. I 
> > stayed away from that like the plague as I found it interesting but  
> > had  no real use for them. 
> > 
> > I just wondered if a psuedo Cordic Rotator might do some of the 
> > math a bit easier? The precsion is limited by the number of 
> > iterations and the precison of  tables for the various functions. 
> > 
> > Neat things one can do with Cordic Math. 
> > 
> > james
> > 
>  ><snip>
> 
> Could be but that goes beyond my area of competence :)  I think that for 
> specific usage as in Mandelbrot set calculations, where more precision 
> is required than ieee doubles can provide, fixed point calculations need 
> to be used. This was covered in detail by Steve Ciarcia in Byte, Nov 
> 1988, p399-406, where he used 8 byte twos complement numbers to increase 
> precision. There is a book "Fractal Creations - 2nd Ed.", by Time Wegner 
> and Bert Tyler, Wait Group Press, ISBN 1-878739-34-4, which contains 
> programs on CD. The math routines are very fast and the CD contains C 
> source code.
> 
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> 
> 
IEEE 754 Extended Double Precision is required to be 80 bit in the 
mantissa. Anything beyond that is optional. I doubt many compilers 
on the market support beyond an 80 bit mantissa. IF I remember 
correctly Double Precision Extended format will support 245 bits of 
mantissa precission. Finding software to do it is the real kicker. 

james