# This function shifts the elements of an array `x'.  The arg `s' is a
# vector -- each of its elements specifies the shift distance for the
# corresponding dimension of `x'.  A positive shift is down or right; a
# negative shift is up or left.  If unspecified, the shift distance is
# zero (meaning no shift).  If `x' is a table, the function is applied
# to each of its members.

circshift = function (x; s)
{
  local (c; ir; ic; nr; nc; sr; sc; y; m);

  s = fill (2; vector (s), 0, 0);

  c = class (x);
  if (c == "matrix")
  {
    nr = x.nr;
    sr = -s[1]%nr;
    if (sr < 0) { sr = nr + sr; }
    ir = integer ((seq(nr)-1+sr) % nr + 1);

    nc = x.nc;
    sc = -s[2]%nc;
    if (sc < 0) { sc = nc + sc; }
    ic = integer ((seq(nc)-1+sc) % nc + 1);

    y = x[ir;ic];

  elseif (c == "vector")

    nc = x.ne;
    sc = -s[1]%nc;
    if (sc < 0) { sc = nc + sc; }
    ic = integer ((seq(nc)-1+sc) % nc + 1);

    y = x[ic];

  elseif (c == "table")

    y = x;
    for (m in members (y)) { y.(m) = self (y.(m); s); }

  else

    y = self (vector (x); s);
  }

  return y;
};