Maxima uses "." for both the commutative vector dot product and for
noncommutative matrix multiplication. If you need both versions of "."
in the same calculation, you might be in trouble.
You can restore "." to be noncommutative using the command 'remove.'
Maxima uses "~" for the vector crossproduct
(%o0) DONE
(%i1) a.b - b.a;
(%o1) A . b - b . A
(%i2) load("vect");
(%o2)
c:/msys/1.0/maxinstall/share/maxima/5.9.0.9beta2/share/vector/vect.mac
(%i3) a.b - b.a;
(%o3) 0
(%i4) remove(".",commutative);
(%o4) DONE
(%i5) a.b - b.a;
(%o5) A . b - b . A
(%i6) vectorsimp(a ~ b + b ~ a);
WARNING: DECLARE VECTOR INDETERMINANTS
NONSCALAR TO AVOID ERRORS & TO GET FULL SIMPLIFICATION
(%o6) 0
Okay, I need to tell Maxima that 'a' and 'b' are not scalars
(%i7) declare([a,b],nonscalar);
(%o7) DONE
(%i8) vectorsimp(a ~ b + b ~ a);
(%o8) 0
If you need to work wih vector components, you can do that too
(%i9) [1,2,3] ~ [4,5,6];
(%o9) [1, 2, 3] ~ [4, 5, 6]
(%i10) express(%);
(%o10) [- 3, 6, - 3]
(%i11)
Maybe this helps.
Barton
Jonathan Stickel <jjstickel@sbcglobal.net>
Sent by: maxima-admin@math.utexas.edu
08/26/2004 01:21 PM
To: maxima@math.utexas.edu
cc:
Subject: [Maxima] matrix and vector operations
but many other desired functions are missing, e.g. outerproduct and
crossproduct
started to implement these functions myself, which is a good way for me
to learn maxima programming. But I'm wondering if someone else has
already done this and made his functions available? The "vect" package
doesn't seem what I want, and I'm concerned about: "Warning: The VECT
package declares "." to be a commutative operator."
Thanks,
Jonathan
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