MATLAB: Sign switching in a sequence

sequence

I have a column vector for example,
A=[10; 30; 30; 40; 60; 70; 50; 50; 60; 20; 20]
What I want to do is count each time a number makes a transition from a smaller number to a large number, to count the numbers of times a number makes a transition from a larger number to a smaller number and the number of times the is no change in numbers.
Any help would be great thanks!

Best Answer

Look at the diff command. It will subtract each element from the next. Look at the sign of that calculation and you will be all set.
>> A=[10; 30; 30; 40; 60; 70; 50; 50; 60; 20; 20]
A =
      10
      30
      30
      40
      60
      70
      50
      50
      60
      20
      20
>> d = diff(A)
d =
      20
       0
      10
      20
      10
     -20
       0
      10
     -40
       0
>> nnz(d > 0)
ans =
       5
>> nnz(d < 0)
ans =
       2
>> nnz(d == 0)
ans =
       3
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