Difference between two successive elements in a matrix

For example, I have a 100 x 3 matrix A

A =
[1 0 542
 1 5 21
 1 10 125
 1 15 6245
 1 20 2678
 1 50 580
 1 55 1205
 1 60 196
… … ...]

I need to find the difference between successive rows in the second column. For example 5-0=5 for the first two rows of the second column and 10-5=5 for the second and third rows o the second column. If the difference is not 5, I need to store that in a counter. I need to count all the rows with difference of more than 5 per column. How do I do that?

[Rik]

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Answer 1

[dpb]

D=diff(A(:,2));
ix=find(D>5)+1;