graphics : How draw a lines with parametricplot,vertical,horizontal lines,version 1.0.
peter.vlasschaert@gmail.com,22/12/2018

xmin : -3$
xmax: +3$
ymin: -5$
ymax:5$

draw :vertical line :
===============

x1(t):= -2;
y1(t):= t;

wxplot2d(
[parametric,x1(t),y1(t),[t,ymin,ymax]],    
[x,xmin,xmax],[y,ymin,ymax]
);

draw :horizontal line :
==================

x2(t):= t;
y2(t):= 1;

wxplot2d(
[parametric,x2(t),y2(t),[t,xmin,xmax]],    
[x,xmin,xmax],[y,ymin,ymax]
);

combination : two graphics
=======================

p1:wxplot2d(
[[parametric,x1(t),y1(t),[t,ymin,ymax]],[parametric,x2(t),y2(t),[t,xmin,xmax]]],
[x,xmin,xmax],[y,ymin,ymax],[same_xy]);

p2:wxplot2d(
[[parametric,x1(t),y1(t),[t,ymin,ymax]],[parametric,x2(t),y2(t),[t,xmin,xmax]]],
[x,xmin,xmax],[y,ymin,ymax],[legend,false]);

p2:wxplot2d(
[[parametric,x1(t),y1(t),[t,ymin,ymax]],[parametric,x2(t),y2(t),[t,xmin,xmax]]],
[x,xmin,xmax],[y,ymin,ymax],
 [style,[points,0.2,blue],[points,0.2,blue]],   
    [legend,false]);

p3:wxplot2d(
[[parametric,x1(t),y1(t),[t,ymin,ymax]],[parametric,x2(t),y2(t),[t,xmin,xmax]]],
[x,xmin,xmax],[y,ymin,ymax],
 [style,[points,0.2,red],[points,0.2,blue]],   
    [legend,false]);

p4:wxplot2d(
[[parametric,x1(t),y1(t),[t,ymin,ymax]],[parametric,x2(t),y2(t),[t,xmin,xmax]]],
[x,xmin,xmax],[y,ymin,ymax],
 [style,[lines,0.4,blue],[lines,0.4,black]],   
    [legend,false]);

general line :
===========

p5:wxplot2d(x,[x,xmin,xmax],[y,ymin,ymax],[same_xy]);

combination :  graphics  ( parametic,function)
=======================================

xmin : -5$
xmax: +5$
ymin: -5$
ymax:5$

a:2$
b:3$

x3(t) := a*cos(t);
y3(t) := b*sin(t);

p4:wxplot2d(
[-x,x,[parametric,x1(t),y1(t),[t,ymin,ymax]],
[parametric,x2(t),y2(t),[t,xmin,xmax]],[parametric,x3(t),y3(t),[t,0,2*π]]],
[x,xmin,xmax],[y,ymin,ymax],
 [style,[points,0.2,blue],[lines,0.4,red],[lines,0.4,blue],[lines,0.4,black],[lines,0.6,blue]]
    , [point_type,bullet],
    [same_xy],[legend,false],grid2d);

rem :  point_type => circle,diamond,bullet...... 'see manuel'