Extracted text: 4. Arrays. In order to test the functions in this question, you will need an array. We can create a three- dimensional test array as follows: testArray <- array(="" sample(="" 1:60,="" 60,="" replace="F)," dim="c(5,4,3)" )="" the="" above="" line="" creates="" a="" 5="" x="" 4="" x="" 3="" array="" of="" integers="" which="" can="" be="" represented="" in="" mathematics="" by:="" {rijk="" :="" i="1,2," ...,="" 5;="" j="1,2," 3,="" 4;="" k="1,2," 3="" }="" note="" that="" apply="" (testarray,="" 3,="" tmpfn)="" means="" that="" the="" index="" k="" is="" retained="" in="" the="" answer="" and="" the="" function="" tmpfn="" is="" applied="" to="" the="" 3="" matrices:="" {xi,j,1="" :1="" xijk="" -="" máx="" xij,k="" i="1" wi,j,k="Xij,k" -="" min="" xij,k="" and="" zj,k="i=1" i="1" (b)="" now="" suppose="" we="" want="" a="" function="" testfn2="" which="" returns="" the="" d2="" x="" d3="" matrix="" {zj.k}="" where="" di="" zj,k="">