Shell Programming and Scripting

a         b         c         d
10.5    20.2    50.4    100.2
200.1  500.4   20.6    10.4

12
50
200

12   a   1
50   c   1
200 a   2

awk -v range=2 '
function adiff(a,b) {if (a>b) return a-b; else return b-a}
NR==FNR {val[$1]; next}
FNR>1 {
  for (f=1; f<=NF; f++)
    for (i in val)
      if (adiff($f,i)<=range) print i, f, FNR-1
}
' FILE2 FILE1

awk '
        NR == FNR {
                A[$1]
                next
        }
        FNR == 1 {
                for ( i = 1; i <= NF; i++ )
                        R[i] = $i
                next
        }
        {
                for ( i = 1; i <= NF; i++ )
                {
                        for ( k in A )
                        {
                                d = ( k > $i ? k - $i : $i - k )
                                if ( d >=0 && d <=2 )
                                        print k, R[i], FNR-1
                        }
                }
        }
' file2 file1