[Scilab-users] vatying color along a curve

[grivet]

Hello,
I am trying to plot a curve using varying colors (or saturations) along 
the way. The curve is computed as a series of segments.
To plot a segment beginning at (xd,yd) and ending at (xf,yf), I have 
tried the following

plot([xd,xf],[yd,yf],"foreground",3);

This works, but, at each call of plot (thousands in my case) Scilab 
emits the following message:

AVERTISSEMENT : Incorrect input : Color vector should be a 3x1 or 1x3 vector
Further, I would like to use colors which do not belong to the default 
color table. If I do

plot([xd,xf],[yd,yf],"foreground",[3,3,3]);

the program stops on the first call to plot with the following error 
message:

addcolor : Type erroné de l'argument d'entrée n°1 : Une structure de 
données de type color_map attendue

I then tried

plot([xd,xf],[yd,yf],"foreground",color_map(3));

the program stops on the first call to plot with the following error 
message:
Variable non définie : color_map

What is the correct syntax? I would like to choose a different color 
vector for each call of plot. Further, the help
sometimes states that color vector elements must be integers from 0 to 
256, sometimes reals between
0 and 1; which is correct ?

Thank you in advance for your time and help.
JP Grivet