Function to check whether an array contains a duplicate of elements

I want to write a function that

- Takes as input an array, the value being checked and the starting element of the array where checking for a duplicate should start

- Returns a logical value to indicate whether the array contains a duplicate of the value being checked (stops checking when one is found)

[the cyclist]

Is this a homework assignment? What have you tried yourself? Maybe we can help your learn MATLAB, rather than do your work for you.

[Walter Roberson]

Okay, go ahead.

Answer 1

[dpb]

function flag=isduplicate(x,v,ix)
  flag=numel(find(x(ix:end)==v))>1;
end

x is vector or if x is array in linear addressing order.

Otherwise, need indexing expression of row, colum, ... for as many dimensions as are greater > 1 in size(x)

If x is floating point, then for robustness, consider ismembertol instead of exact equality or write a tolerance expression.

[the cyclist]

I think you meant to assign the value to the output variable flag.

[dpb]

Yeah, thanks...

[Walter Roberson]

Note that this might not behave as expected if there are NaN in the array.