Sin Z2 Twin Galaxies

Newton's method with complex relaxation m = 1 - 0.5i applied to f(z) = sin(z^2) - 1. Every root is double, so convergence is linear, and the local error map multiplies by 0.5 + 0.25i each step, a contraction of 0.559 with a 26.6 degree twist that curls each basin into a spiral arm. The function is even, so the frame has exact 180 degree rotational symmetry. Roots on the real axis take a magenta ramp and roots on the imaginary axis a cyan one.