selecting mid points

I have a values

F=[3 5 6 15 17 21 35 45 46 51 56 57 66 70 71 ]

now i want to calculate the mid points that is

i have to take 2 values that is(3,5)and (5,6) cal mid point(4,5.5)

next (5,6),(6,15) mid point is(5.5,10.5)

(6,15)and(15,17) mid point(10.5,16)

(15,17)and(17,21) mid point is(16,19)

and so on

please help

Answer 1

[Image Analyst]

Use convolution (a sliding window filter), conv():

F=[3 5 6 15 17 21 35 45 46 51 56 57 66 70 71 ]
F_mid = conv(F, [0.5 0.5], 'valid')

Results:

F =
     3     5     6    15    17    21    35    45    46    51    56    57    66    70    71
f_mid =
  Columns 1 through 12
    4.0000    5.5000   10.5000   16.0000   19.0000   28.0000   40.0000   45.5000   48.5000   53.5000   56.5000   61.5000
  Columns 13 through 14
   68.0000   70.5000

[kash]

Thanks a lot now can u please tell how to combine as

4,5.5

5.5,10.5

10.5,16

so on