DOS program, "Orbits", Color Schemes

In a previous page, for the options pDIV, pALL, and pPRM, the slope M of f ^k, where k is the prime period of the periodic point determines the color used to plot that point. Different coloring schemes are set by changing the value of (capital) K at the bottom of the screen. K=1 by default. Other values of K select different coloring schemes. Those based on the slopes are listed in the following table:
K (scheme #) M > 1
(repelling pt)
0 < M < 1
(attracting pt)
-1 < M < 0
(attracting pt)
M < -1
(repelling pt)
1 red dot yellow dot pink dot purple dot
4 red plus sign yellow little square pink bigger square purple minus sign
5 fat red dot fat yellow dot fat pink dot fat purple dot
7 dark red dot brite white dot brite white dot dark red dot
0 red dot purple dot purple dot red dot
Color scheme K=5 is like K=1 except bigger dots are used. K=0 is used to make the (relatively scarce) attracting cycles really stand out.

Other color schemes are as follows:

K=2: The slope M is used, but now steep positive slopes get dark reds; as the slopes level off, the colors progress towards yellow and then white. As the slopes become negative, the colors darken again, through blues and purples.

K=3: Here the prime period of the point defines the color; when pALL is used, this makes it easy to identify which curves identify points of which prime periods. K=8 does the same thing, using thicker dots.

K=6: Points of prime period N alone are shown brightly; points of lesser periods appear dark (using pALL or pDIV)


Now, for pORG, there are a few differences. First is, that all slopes are computed using f ^N (where N is the value of "iterate" set by the user) instead of f ^k, where k is the prime period of the point. That said, K=0,1,4,5 and 7 work as for pPRM, pALL, and pDIV. K=2 again uses varying colors but chosen slightly differently. K=6 just plots all points in the same color.

K=3 is the only new one. Here at every point (C,x) on the screen, the color is chosen based on how far f_C(x) is from the Nth iterate of f_C(x). An example is shown below, with N=4. The outline of the "k|4" picture (all period 1,2,4 prime periodic points) is clearly visible.

completely colored period 4 bifurcation diagram


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© 2001 by Chip Ross
Associate Professor of Mathematics
Bates College
Lewiston, ME 04240