Hi JB,
Could you please try the following script which creates a line segment object with 
specified coordinates of the starting point, slope, and length:GetN (X1) xx1
     (Y1) yy1
     (Slope) slope1
     (length) length1;
xx2=xx1+length1*cos(atan(slope1));
yy2=yy1+length1*sin(atan(slope1));
draw -l {xx1,yy1,xx2,yy2};Hope you can get what you wanted by this script.
--Hideo Fujii
OriginLab