Jim Muth's DivideBrot5 formula makes nice fractals. Fractint says his *built-in-type* formula is: z(n+1)=sqr(z(n)) / (z(n)^(-(a-2)) + (b+10^(-20)))+pixel For these fractals I set the parameters: a=7 and b=1. Default values are: a=2 and b=0. I couldn't resist doing a few zooms while I was trying out Jonathan's new version of FractSDL: "SDL2-fractint-20.05alpha-2019-09-15". View these fractals full size to see their original pixels. Firefox displayed my images OK with my URL's HTTP://, but Chrome looks like it changes my URLs to HTTP*S*:// and my hosting provider's HTTPS certificate looks like it aged out last month -- and Chrome now gives a certificate error: NET::ERR_CERT_COMMON_NAME_INVALID After I got the above error -- to view my images in Chrome I think I recall I had to: - click Advanced, and then click Chrome's: - "Proceed to www.emarketingiseasy.com (unsafe)" Even after clearing Chrome's cache and closing and reopening Chrome, Google has remembered that I want to view images on my server and won't give me the error again -- so I'm not able to provide you with certainty the exact sequence of clicks I used to see my images using Chrome. Sorry. I use a link shortener because long links get chopped into two pieces by the email/list process -- neither of which work. DivBrt01.gif: MaxIter changed from the default 150 to 500, Color map=blues.map: http://tinyurl.com/DivBrt01 or: http://www.emarketingiseasy.com/Fractint/2019-09-15_SDL2-fractint-20.05alpha /DivBrt01.gif DivBrt02: Upper right quadrant of DivBrt01: MaxIter=1000: http://tinyurl.com/DivBrt02 Mike Frazier and I enjoy looking into what tendrils do in fractals. They often surprise us: Here are some provided by Jim's dividebrot5 formula: DivBrt03: Lower left corner of DivBrt02: MaxIter=2000, Periodicity=0: http://tinyurl.com/DivBrt03 DivBrt04: A little further zoom shows the interesting "tendril activity" better: MaxIter=2000, Periodicity=0: http://tinyurl.com/DivBrt04 DivBrt05: The upper tendril pair in DivBrt04: MaxIter=2000, Periodicity=0: http://tinyurl.com/DivBrt05 DivBrt06: The upper tendril pair on keeps curling around as you zoom in: MaxIter=2000, Periodicity=0: http://tinyurl.com/DivBrt06 DivBrt08: *Click* the image and *scroll* down to see the center of this 4096x3072 gif. When I tried anti-aliasing, it made the narrowest features dim down too much. Also, when the tendril become sub-pixel in size (but you hope for an occasional lucky hit/sample on the tendril,) I think the very dark area of the color map happens just when you want bright pixels to make them show up -- and perhaps MaxIter still isn't high enough. MaxIter=4000, Periodicity=0: http://tinyurl.com/DivBrt08 OK. Enough infinite curling. DivBrt09: The lower convergence of tendrils in DivBrt04: *Click* the image and *scroll* down to see the center. The tendrils pass through/over/under/? each other! Some tendrils in the "swarms" of tendrils coming in from the left and right peter out, likely because I didn't set MaxIter high enough. Note also that the tendril from the left -- after crossing the downward pointing one -- continues on to the right, attempting to meet its mate. Who knows where the downward-pointing tendril is going? Does it, too, have a secret rendezvous? MaxIter=4000, Periodicity=0, 4096x3072: http://tinyurl.com/DivBrt09 Thank you, Jim, Jonathan! - Hal Lane ######################## # hallane@earthlink.net ########################