I have solved the question but there is an error.....so plz give me a solution

Write a function called neighbor that takes as input a row vector called v and creates another row vector as output that contains the absolute values of the differences between neighboring elements of v. For example, if v == [1 2 4 7], then the output of the function would be [1 2 3]. Notice that the length of the output vector is one less than that of the input. Check that the input v is indeed a vector and has at least two elements and return an empty array otherwise. You are not allowed to use the diff built-­‐in function.

function d = neighbor(v)

for ii = 1:length(v)-1

   d(ii) =  abs(v(ii+1) - v(ii));

   end
   end

Feedback: Your function performed correctly for argument(s) [1 2 3 4]

    Feedback: Your function performed correctly for argument(s) [2 1]

    Feedback: Your function performed correctly for argument(s) [1 -2 3]

    Feedback: Your function performed correctly for argument(s) [5 -3 6 -7 1 4 -4 6 -5 -1]

    Feedback: Your function performed correctly for argument(s) [0.775665774190202 0.46043860784642 0.637754980094595 0.21592913366455 0.0321676971373623 0.777337876450925 0.979770397784413 0.221076297004035 0.063923583412422 0.129378479212439]

    Feedback: Your function made an error for argument(s) [1 2;3 4]

    Your solution is _not_ correct.

[Jan]

Did you search in the internet to find a solution? You would find http://www.mathworks.com/matlabcentral/answers/219445-how-to-make-a-function-that-calculate-consective-difference-of-elements-of-a-vector

[Darshan Kanungo]

thanku...its a simple and i understand it.

Answer 1

[Jan]

The question is: "a function [...] that takes as input a row vector [...]". But [1 2;3 4] is not a row vector. Therefore your function is correct, but the feedback test is wrong.

So what do you want to do? Do you want to create a function which satisfies the question or the automatic test?

[John D'Errico]

As defined by the specs:

"Check that the input v is indeed a vector and has at least two elements and return an empty array otherwise."

Answer 2

[Image Analyst]

The problem statement is bad and should be corrected by the instructor. And you can tell him I said that.

The statements "takes as input a row vector" and "Check that the input v is indeed a vector" are ambiguous. Checking that v is a vector, with the isvector() function, is not sufficient to make sure that you passed in a row vector, since a column vector will also "pass". So if you passed in a column vector and checked if it's a vector, that would pass that requirement, then the first requirement would not be satisfied - hence the ambiguity/contradiction. For it to be consistent, the second test should say "Check that the input v is indeed a row vector" . For that, you can use the function isrow() rather than is vector. A user passing in a column vector would not pass the test and you should throw up a warning message with warndlg().

if ~isrow(v)
    % v is a multi-dimensional array or a column vector.
    uiwait(warndlg('Error: v is not a row vector'));
    return;
end