如何改变z轴的数值，貌似persp函数不能添加z轴区间长度？

mv.NE <- mvdc(normalCopula(-0.9179715), c("lnorm", "lnorm"),
              list(list(mean =285.5063, sd =1376.559), list(mean =2.196738, sd =1.337626)))
dim(mv.NE)
persp  (mv.NE, dMvdc, ylim = c(0, 15), xlim=c(0.5,1.2), main = "dMvdc(mv.NE)")
这是图形效果