Xref: utzoo comp.theory:1400 sci.math:14651 alt.fractals:821 Path: utzoo!utgpu!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!rpi!crdgw1!sixhub!davidsen From: davidsen@sixhub.UUCP (Wm E. Davidsen Jr) Newsgroups: comp.theory,sci.math,alt.fractals Subject: Re: High precision Mandelbrot set Message-ID: <2862@sixhub.UUCP> Date: 10 Jan 91 23:56:33 GMT References: <1991Jan8.142354.1732@pegasus.com> Reply-To: davidsen@sixhub.UUCP (bill davidsen) Followup-To: comp.theory Organization: *IX Public Access UNIX, Schenectady NY Lines: 24 In article <1991Jan8.142354.1732@pegasus.com> shaw@pegasus.com (Sandy Shaw) writes: | | When one does a "zoom" on parts of the Mandelbrot set one reaches a | point when due to the limitations of precision of the machine(usually | 64 bit IEEE floating point) one can gain no further detail from the image. Well, you can go a little more if you have an FPU. I took one of my early mandelbrot calculators, which output a dataset for viewing elsewhere, and redid the innermost loop in assembler. Not only did rewriting that part (about 11 instructions) make the overall program 40% faster, but by doing all of the calculations in the stack of the 80287 I was able to use the IEEE 80 bit "intermediate result" accuracy which gave me another 16 bits! I have discovered that good books on programming the [23]87, or 68882 are non-existant. There are a few usable books around, but that's about it. It's a cheap way to do it, and at the time UNICOS (Cray2) C didn't have double, so I actually got better precision on an AT than a Cray2, just a few orders of magnitude slower. -- bill davidsen - davidsen@sixhub.uucp (uunet!crdgw1!sixhub!davidsen) sysop *IX BBS and Public Access UNIX moderator of comp.binaries.ibm.pc and 80386 mailing list "Stupidity, like virtue, is its own reward" -me