/* 0*x, 0/x, x*0, MOD(0,x) => 0. */
else if (((n->type == OP_MUL || n->type == OP_DIV || n->type == OP_MOD_nn)
&& eq_double (n->args[0], 0.))
/* 0*x, 0/x, x*0, MOD(0,x) => 0. */
else if (((n->type == OP_MUL || n->type == OP_DIV || n->type == OP_MOD_nn)
&& eq_double (n->args[0], 0.))