Subscript indices must either be real positive integers or logicals

i am trying to add column of a large matrix using sum instruction but is getting this error "Subscript indices must either be real positive integers or logicals." kindly suggest me a way out

q =

     0    76
     0    76
     0    76
     0    76
     0    76
     0    76
     0    76
    55    21
    57    19
    57    19
    57    19
    56    20
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    11    65
    10    66
    11    65
    11    65
    11    65
    11    65
    10    66
    10    66
     9    67
     9    67
     8    68
     8    68
     7    69
     6    70
     6    70
     5    71
     5    71
     3    73
     0    76
     0    76
     0    76
     0    76
     0    76
     0    76
     0    76
     0    76
     0    76
     0    76
     0    76
     0    76
>> pri=sum(q)
Subscript indices must either be real positive integers or logicals.

Answer 1

[Azzi Abdelmalek]

You have probably used sum as a variable in your code. Check it by typing

sum

Answer 2

[Image Analyst]

You probably redefined sum to be a variable or function in your code, thus destroying it, or actually just using yours in preference to the built-in sum() function. Try putting these lines in and seeing what it says.

whos sum
which -all sum