Whether to scale tangent vector length by the value of
alpha
...
Additional arguments passed to points3d and/or
segments3d
Details
Tangent vectors are plotted by segments3d and centered on the
relevant point. Points are plotted by points3d.
color will be recycled by points3d and segments3d.
However in the special case that color has length equal to the
number of points in x, then it will be duplicated before being
passed to segments3d so that the result is that each vector is
coloured uniformly according to color (since segments3d expects 2
colours for each line segment, blending them if they are different).