The last post received a comment, so I thought the readers could like to see anything more about how to plot vectors.
Let's use the Scilab's text editor, click the 'Editor' button and write the scripts, look the images.
Read the buttons for use the editor's resources.
Now, let's see what happens when the following script is executed:
r = 0.1:0.1:10;
w = %pi/10;
x_i = 0;
y_i = 0;
for t = 1:length(r),
x_f = r(t)*cos(w*t);
y_f = r(t)*sin(w*t);
champ(x_i, y_i, x_f - x_i, y_f - y_i, 0.1);
x_i = x_f;
y_i = y_f;