Mike,
Thanks for all the suggestions on getting the latest version of the code. When I read there was some tool that help manage the source I guessed that it was not available on a Mac. I kept downloading things until I found a tar.gz file that decompressed into xfractint-20.04p9 so I think I now have the latest source. I don't care which platform it is for since I am only using it to figure out algorithms. Unfortunately, this code looks exactly the same in the area I am having a problem with.
Do a Google search for "mac svn client". The Wikipedia page that compares svn clients includes KDEsvn, Qsvn, Subcommander svnX, WebSVN, and xcode (included with OS X 10.5).
I have been trying to figure out how outside=tdis works. The documentation is vague on outside=tdis and trying to guess the algorithm by comparing images has proven futile. I looked in detail at the code in calcfrac.c and this is what I see. It looks very simple. I pasted together the relevant parts so it is easy to see all together. ... I don't think I implemented anything wrong here. The image I get has a color index that changes much faster than the correct image. Its not off by a fixed number or a ratio or any other good clue as to what is wrong. I was hoping someone here might have an idea of something outside this code that could affect the results. If not, no worries, I will just keep looking.
That's all the right code. How are you determining the bailout? We use the following, or something similar (from fractals.c): int near fpMODbailout(void) { tempsqrx=sqr(new.x); tempsqry=sqr(new.y); magnitude = tempsqrx + tempsqry; if(magnitude >= rqlim) return(1); old = new; return(0); } Where rqlim normally defaults to 4. Jonathan