Generating permutations of arr in lexicographic order in C#

gistfile1.cs

public IEnumerable<int[]> Permut(int[] arr){
            while (true){
                yield return arr;
                var j = arr.Length  - 2;
                while (j >= 0 && arr[j] >= arr[j+1]) j--;

                if (j < 0) break;

                var l = arr.Length -1;
                while (arr[j] >= arr[l]) l--;

                var tmp = arr[l]; arr[l] = arr[j]; arr[j] = tmp;

                var k = j +1;
                l = arr.Length -1;
                while (k < l){
                    var t = arr[k];
                    arr[k] = arr[l];
                    arr[l] = t;
                    k++;
                    l--;
                }

            }

        }