Another service from Omega

Lines and Planes in 3D


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A line is determined by a direction vector v and a position vector u.


> with(linalg):


Warning: new definition for   norm
Warning: new definition for   trace



> v := vector(3); u := vector(3);

                             v := array(1 .. 3, [])

                             u := array(1 .. 3, [])




Yes, this is the way in which maple tells that v and u are two arbitrary vectors in 3 dimensional space.

The equation of the line with direction v and passing through u is:


> Line := { u + t*v};


                               Line := {u + t v}




This is the set of all the vectors of the form:
"position vector + a scalar multiple of the direction vector". The scalar "t" is a parameter that can take any value from -infinity to infinity. The position vector of every point on the line can be written as a function of the parameter "t" as follows:


> L := t -> u + t*v;


                               L := t -> u + t v



> L(0);

                                       u



> L(1);

                                     u + v




To see the coordinates of L(t) in the standard basis, just evalm:


> evalm(L(t));


                [ u[1] + t v[1], u[2] + t v[2], u[3] + t v[3] ]




The vector L(t) can be interpreted as the position at time "t" of a particle moving with constant velocity vector v that is found at position u at an innitial time 0. The following two commands will display a picture of the line with velocity vector [1,-2,,3] and position vector [2,1,-1].


> with(plots);


 [animate, animate3d, conformal, contourplot, cylinderplot, densityplot,

     display, display3d, fieldplot, fieldplot3d, gradplot, gradplot3d,

     implicitplot, implicitplot3d, loglogplot, logplot, matrixplot, odeplot,

     pointplot, polarplot, polygonplot, polygonplot3d, polyhedraplot, replot,

     setoptions, setoptions3d, spacecurve, sparsematrixplot, sphereplot,

     surfdata, textplot, textplot3d, tubeplot]




Notice that the next command "spacecurve" was loaded with the "with" above.


> spacecurve([2+t, 1-2*t, -1+3*t], t=-4..4, axes=NORMAL, color=RED);

picture a picture here

Link to the commands in this file
Carlos Rodriguez <carlos@math.albany.edu>
Last modified: Thu Sep 12 13:02:43 EDT 1996