# Seven Brothers

Following up on Contours, A Mathematical Coloring Book, here's another contour plot for coloring:

The PDF version is here. The copyright is Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International.

Like the other contour plots in the book, this plot was created using Sage. Here's the Sage notebook code, in case you want to play with the plot.

```
a = exp(2*pi/3*I)
f(z) = sin(z^7 + a)
f = fast_callable(f, domain=CDF, vars='z')
def ff(x, y):
return f(CDF(x, y)).real(), f(CDF(x, y)).imag()
def iterate(func, n):
def g(x, y):
for i in range(n):
x, y = func(x, y)
return abs(CDF(x,y))
return g
G = Graphics()
for j in range(1, 6):
G += contour_plot(iterate(ff, j), (-1.8, 1.8), (-1.8, 1.8),
contours=[0.2, 0.5, 1], fill=False)
G.show(frame=True, axes=False, aspect_ratio=1)
```

# Contours: A Mathematical Coloring Book

Here is a mathematical coloring book I recently made. It contains black and white pictures generated by mathematical formulas which you color in for fun. Best printed on size A4 paper or bigger. Enjoy and share!

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