1 Here is a comparison matrix which shows a case in which 2 it is possible for the forward and backward scan in `diag' 3 to meet along a nonzero length of diagonal simultaneous 4 (so that bdiag[d] and fdiag[d] are not equal) 5 even though there is no snake on that diagonal at the meeting point. 6 7 8 85 1 1 1 159 1 1 17 9 1 2 3 4 10 60 11 1 2 12 1 13 2 2 3 4 14 71 15 3 3 4 5 16 85 17 4 3 4 5 18 17 19 5 4 5 20 1 21 6 4 5 6 22 183 23 7 5 6 7 24 10 25 8 6 7 26 1 27 9 6 7 8 28 12 29 7 8 9 10 30 13 31 10 8 9 10 32 14 33 10 9 10 34 17 35 10 10 36 1 37 10 9 10 38 1 39 8 10 10 10 40 183 41 8 7 9 9 9 42 10 43 7 6 8 9 8 8 44 1 45 6 5 7 7 46 1 47 5 6 6 48 1 49 5 5 5 50 50 51 5 4 4 4 52 1 53 4 3 3 54 85 55 5 4 3 2 2 56 1 57 2 1 58 17 59 5 4 3 2 1 1 60 1 61 1 0 62 85 1 1 1 159 1 1 17 63 64 65 66 67 68 69 70 71 72