getting axis equal?



I get the below error when I try Bart Vandewoestyne's example.

(%i1) restart; load(vect); load(draw);

(%o1) restart
(%i2)
(%o2) "C:/program1/maxima/share/maxima/5.23.2/share/vector/vect.mac"
(%i3)
(%o3) "C:/program1/maxima/share/maxima/5.23.2/share/draw/draw.lisp"
(%i4) mymax: 8;

(%o4) 8
(%i5) n: [0, 0, 1];

(%o5) [0,0,1]
(%i6) E: [1, 2, -2]; H: [2, 1, 2];

(%o6) [1,2,-2]
(%i7)
(%o7) [2,1,2]
(%i8) nxE: express(n~E);  Exn: express(E~n);  Exnxn: express((E~n)~n);

(%o8) [-2,1,0]
(%i9)
(%o9) [2,-1,0]
(%i10)
(%o10) [-1,-2,0]
(%i11) nxH: express(n~H);  Hxn: express(H~n); nxnxH: express(n~(n~H));

(%o11) [-1,2,0]
(%i12)
(%o12) [1,-2,0]
(%i13)
(%o13) -[-1,2,0] ~ [0,0,1]
(%i14) sum1: Exnxn+Hxn;  sum2: nxE+nxnxH;

(%o14) [0,-4,0]
(%i15)
(%o15) [-2,1,0]-[-1,2,0] ~ [0,0,1]
(%i16) draw3d(proportional_axes=xyz,
       axis_3d=true,
       xtics = 1, ytics = 1, ztics = 1,
       /* xrange=[-mymax, mymax],
       yrange=[-mymax, mymax],
       zrange=[-mymax, mymax], */
       color=black,
       vector([0,0,0], n),
       label(["n", n[1], n[2], n[3]]),
       color=blue,
       vector([0,0,0], E),
       label(["E", E[1], E[2], E[3]]),
       vector([0,0,0], H),
       label(["H", H[1], H[2], H[3]]),
       color=red,
       vector([0, 0, 0], nxE),
       label(["nxE", nxE[1], nxE[2], nxE[3]]),
       vector([0, 0, 0], Exn),
       label(["Exn", Exn[1], Exn[2], Exn[3]]),
       vector([0, 0, 0], Exnxn),
       label(["Exnxn", Exnxn[1], Exnxn[2], Exnxn[3]]),
       vector([0, 0, 0], nxH),
       label(["nxH", nxH[1], nxH[2], nxH[3]]),
       vector([0, 0, 0], nxnxH),
       label(["nxnxH", nxnxH[1], nxnxH[2], nxnxH[3]]),
       vector([0, 0, 0], Hxn),
       label(["Hxn", Hxn[1], Hxn[2], Hxn[3]]),
       color=green,
       vector([0,0,0], sum1),
       label(["sum1", sum1[1], sum1[2], sum1[3]]),
       vector([0,0,0], sum2),
       label(["sum2", sum2[1], sum2[2], sum2[3]]));

draw (vector): coordinates are not correct
 -- an error. To debug this try: debugmode(true);
(%i17)


Below is the Maxima version that I am using:

Maxima version: 5.23.2
Maxima build date: 11:22 2/2/2011
Host type: i686-pc-mingw32
Lisp implementation type: GNU Common Lisp (GCL)
Lisp implementation version: GCL 2.6.8

####################

[Maxima] getting axis equal?
Bart Vandewoestyne Bart.Vandewoestyne at telenet.be 
Thu Mar 3 08:59:00 CST 2011 


Hello all,

I am plotting some vectors in 3D space with the draw3d command,
but somehow the data units on the x, y and z-axis are not equal.
I would like to get them equal so that it is easier to see which
vectors are perpendicular to each other.  So what I basically
need is a Maxima equivalent for Matlab's 'axis equal' command.

I have tried adding the

  proportional_axes=xyz

option, but this didn't seem to help.

My .wxm file (for wxMaxima 0.8.5) is online at

http://www.kuleuven-kortrijk.be/~bartv/silver_mueller.wxm

I'm not using Maxima that often, so any other comments on my
Maxima coding style and improvements on my code are welcome.

Regards,
Bart

-- 
	"Share what you know.  Learn what you don't."