数学图形(1.12) 螺线

在平面极坐标系中，如果极径ρ随极角θ的增加而成比例增加（或减少），这样的动点所形成的轨迹叫做螺线。
最常见的螺线有阿基米德螺线、对数螺线、双曲螺线等。

阿基米德螺线

vertices = 1000 t = from 0 to (20*PI) a = 0.05 r = a*t x = r*sin(t) y = r*cos(t)

等角螺线

vertices = 12000 t = from (-20*PI) to (20*PI) b = 0.05 r = pow(E, b*t) x = r*sin(t) y = r*cos(t)

对数螺线

vertices = 1000 a = 1.0 b = 1.1 t = from 0 to (15*PI) p = a*pow(b,t) x = p*sin(t) y = p*cos(t)

费马螺线

vertices = 12000 r = from -10 to 10 t = r*r x = r*sin(t) y = r*cos(t)

连锁螺线

vertices = 12000 r = from -10 to 10 k = 1.0 t = k/(r*r) t = limit(t, -10*PI, 10*PI) x = r*sin(t) y = r*cos(t)

双曲螺线

#极径与极角成反比的点的轨迹称为双曲螺线。 vertices = 10000 a = 16.0 t = from 0.5 to (200*PI) x = a*cos(t)/t y = a*sin(t)/t

圆周渐伸线,貌似它与阿基米德螺线是相同的.

vertices = 1000 r = 1.0 t = from 0 to (20*PI) x = r*[cos(t) + t*sin(t)] y = r*[sin(t) - t*cos(t)]