void cross (iscross) GRIDOPTS.C Level 1
int iscross  = 0 if crossed axes are not desired (default).
 = 1 if crossed axes are desired.
cross() makes the axes cross if either axis goes through zero. Thus, log axes cannot be crossed. GraphiC is smart enough to disable cross() when it cannot apply. This routine does not affect 3-D plots. The internal flag is reset to 0 after each plot.