tit:leveldata
type:$type_both
alias:levelpoints
syntax:!leveldata size `xsize,ysize' ranges `x1,x2,y1,y2' function `f(x,y)' [levels `l1,l2,...']
mean:¼ÆËã `f(x,y)' ÔÚˮƽ `l1,l2,...'\
(ĬÈÏÖµÊÇÒ»¸öˮƽ 0) ´¦µÄˮƽÇúÏßÉϵĵãµÄ×ø±ê. <p>\
¼ÆË㷶Χ´Ó `(x1,y1)' ÖÁ `(x2,y2)',\
¼ÆËãͼÐÎÄÚ¹ØÓÚ `xsize,ysize' µÄÕûÊýλÖõĵã. <p>\
²ÎÊýÇø¶ÎµÄ´ÎÐò²»ÖØÒª, µ«³ýÁËˮƽÍâ¶¼ÊDZØÐëµÄ.