How to write an if statement that checks if array is real and positive?

I have an array called amplitude with an N*1 matrix, N is a positive and integer number

This is my code:

 if sum(A<0)~=0 || (A~=isreal(A))
    error('Amplitude must be real and postive elements');
 end

it doesn't seem to work, could use help?

Answer 1

[Geoff Hayes]

Brian - since A is an array, you will want to use the all function to ensure that all elements are positive and all elements are real. For example,

 if ~all(isreal(A)) || ~all(A>0)
     error('Amplitude must have only real and positive elements');
 end

Try the above and see what happens!

With your code, with sum it seems like you want to check to see if the sum of all negative elements is not zero which may be okay, but should be discouraged when comparing singles or doubles to an integer (use a tolerance instead). And your second condition is trying to compare all elements of A against an array of ones and zeros (with a one indicating a real number). Why?

[Walter Roberson]

Hypothetically,

any(A(:)<=0)

could be faster than

   ~all(A>0)

Watch out for the fact that A is 2D but all() and any() act on a single dimension.