Function circle

cython/fem/main.py:97–102

(N, R)

    # https://rufat.be/triangle/examples.html
    # effective: qpa0.1
    def circle(N, R):
        i = np.arange(N)
        theta = i * 2 * np.pi / N
        pts = np.stack([np.cos(theta), np.sin(theta)], axis=1) * R
        seg = np.stack([i, i + 1], axis=1) % N
        return pts, seg

    pts0, seg0 = circle(30, 1.4)
    pts1, seg1 = circle(16, 0.6)