数学图形(1.36)曳物线

曳物线,从曲线C上某一动点P的切线与某一定直线l的交点Q到点P的线段长恒为定值,则称曲线C为曳物线(tractrix)。直线l为其渐近线。

写法1:

vertices = 1000

t = from (-2*PI) to (2*PI)
x = 2/[E^t+E^(-t)]
y = t-tanh(t)

x = limit(x, -20, 20)
y = limit(y, -20, 20)

写法2:

vertices = 1000

t = from (-2*PI) to (2*PI)
x = sech(t)
y = t-tanh(t)

x = limit(x, -20, 20)
y = limit(y, -20, 20)