[Maxima-discuss] Strange semantics when a macro calls other macro

[Eduardo O. <edu...@gm...>]

Hi list,

can anyone help me to understand what is happening in the program
below?

  mkmatrix0(xs, ys, expr) :=
    buildq([xs,ys,expr],
      apply(matrix,
            makelist(makelist(expr, splice(xs)),
                     splice(ys))))$

  mkmatrix (xs, ys, expr) ::= mkmatrix0 (xs, ys, expr)$

  Dx : x - x0;
  Dy : y - y0;
  [x0,y0] : [3,2];
  mkmatrix ([x,0,x0+1], [y,y0+1,0,-1], [x,y]);
  mkmatrix ([x,0,x0+1], [y,y0+1,0,-1], ev([Dx,Dy]));
  a : mkmatrix ([x,x0-1,x0+1], [y,y0+1,y0-1,-1], [x,y]);
  b : mkmatrix ([x,x0-1,x0+1], [y,y0+1,y0-1,-1], ev([Dx,Dy]));

  aroundx0y0(expr) ::= mkmatrix ([x,x0-1,x0+1], [y,y0+1,y0-1,-1], expr)$

  c : aroundx0y0([x,y]);
  d : aroundx0y0(ev([Dx,Dy]));

I was expecting that a and c would return the same matrix, and b and d
would return the same (other) matrix, but no... in the lines that
calculate a and b the symbols x and y are become bound variables
inside the two "makelist"s, but in the lines that calculate c and d
the x and the y don't change...

Thanks in advance!
  [[]], Eduardo...