Hello can somebody tell me what I am doing wrong?

I am trying to write a MATLAB program using a forloop to determine the number of values that are positive, negative, and the number of values that equal zero in a vector containing 'N' elements. I can't get it to work.

format compact

v = input('Enter the number of elements in the Vector: ');
a = input('Enter the Array:');

for i = 1:length(a)
     if v > 0

           fprintf('v>0',i)
       elseif v < 0

           fprintf('v<0',i)
       else

           fprintf('v=0',i)
       end
  end

Answer 1

[Jos (10584)]

This is a working for-loop, which prints out something that resembles your goal:

   a = input('Enter the Array:');
    for i = 1:length(a)
         v = a(i) ; % get the i-th element of a
         if v > 0
               fprintf('v>0',i)
           elseif v < 0
               fprintf('v<0',i)
           else
               fprintf('v=0',i)
           end
      end

However, the next step is to learn to do this in a matlab-like way

V = input('Enter the Array:');
disp('V < 0') ;
idx = find(V<0) ; % all at once
disp(idx) ;

Answer 2

[Muthu Annamalai]

Hi Pittman,

In addition to the answer by Jos, I have some observations for you:

1. Enter the data at your runtime as '5', and '[1,2,3,4,5]' (not including the quotes ofcourse)
2. When you use fprintf see MATLAB documentation , you want code like,

   fprintf('v < 0 : %d',i);

Ofcourse your code is written in a more C-like fashion, whereas using MATLAB we like to vectorize operations since matrices are native types.

HTH.