# [Maxima] Expanion of vector expressions

Soegtrop, Michael michael.soegtrop at intel.com
Thu Apr 26 03:59:28 CDT 2012

Dear Maxima Users,

I came across a problem with vector simplification (using maxima 5.25.1, I have problems with maxima 5.26). For products of a scalar and a vector, it depends on the length of the scalar expression, if it is distributed over the vector or not.

E.g. with a 5 element denominator I get

(%i1) [x,y,z]/(a+b+c+d+e);

(%o1) [x/(e+d+c+b+a),y/(e+d+c+b+a),z/(e+d+c+b+a)]

And with a 6 element denominator I get

(%i2) [x,y,z]/(a+b+c+d+e+f);

(%o2) [x,y,z]/(f+e+d+c+b+a)

I found no way to expand such a vector*scalar expression, e.g. expand, vectorsimp with expandall:true don't work. This is especially inconvenient when I want to retrieve an element of the vector as in

(%i3) ([x,y,z]/(a+b+c+d+e))[1];

(%o3) x/(e+d+c+b+a)

but

(%i4) ([x,y,z]/(a+b+c+d+e+f))[1];

(%o4) ([x,y,z]/(f+e+d+c+b+a))[1]

Is there a way of doing this without writing my own function for this?

Thanks & best regards,

Michael