Re: Plotting Lines in 3D

[Thomas D. Dean]

On 08/06/15 06:40, Richardson, Anthony wrote:

<snip>

> In a separate post I give:
>
> plot3([X(:,1)'; X(:,4)'], [X(:,2)'; X(:,5)'],[X(:,3)'; X(:,6)']);
>
> or (to plot all lines in the same color):
>
> plot3([X(:,1)'; X(:,4)'], [X(:,2)'; X(:,5)'],[X(:,3)'; X(:,6)'],'b');

I was having problems getting my head around the arguments, the content 
and shape.

From help plot3, the simplest form

     Many different combinations of arguments are possible.  The
     simplest form is

          plot3 (X, Y, Z)

     in which the arguments are taken to be the vertices of the points
     to be plotted in three dimensions.  If all arguments are vectors of
     the same length, then a single continuous line is drawn.  If all
     arguments are matrices, then each column of is treated as a
     separate line.  No attempt is made to transpose the arguments to
     make the number of rows match.

The applicable sentence:  If all arguments are matrices, then each 
column of is treated as a separate line.

octave:815> U=[X(:,1)'; X(:,4)'];
octave:816> V=[X(:,2)'; X(:,5)'];
octave:817> W=[X(:,3)'; X(:,6)'];
octave:818> plot3(U,V,W)

The first column of U,V,W, respectively define the first line.

L1_x1 = U(1,1)
L1_y1 = V(1,1)
L1_z1 = W(1,1)

L1_x2 = U(2,1)
L1_y2 = V(2,1)
L1_z2 = W(2,1)

etc.

My code is less than 30 lines.  Is this a good example for plot3?

Tom Dean