Undeclared function or variable.

When I run the function (given below), it shows an error:

" Undefined function or variable 'class_pointb'"

(The main code where the function is called is also attached. )

function counter = check(edge,point,n)
count_edge = zeros(1,10,4);
fit = 4;
interval = n / 10;

    div = point(1,1) / interval;

    for i = 1:10
        if div >= i && div < i + 1
            class_pointa = i;
            break
        end
    end

    div = point(1,2) / interval;

    for i = 1:10
        if div >= i && div < i + 1
            class_pointb = i;
        end
    end

    if edge(1) == 1
        count_edge(1,class_pointa,1) = count_edge(1,class_pointa,1) + 1;
        a = 1; 
    end

    if edge(2) == 1
        count_edge(1,class_pointb,1) = count_edge(1,class_pointb,1) + 1;
        b = 1;
    end

    if count_edge(1,class_pointa,a) < fit && count_edge(1,class_pointb,b) < fit
        counter = 1;
    else
        counter = 0;
    end
end

I do not understand this because i think i have defined it as : class_pointb = i; How can it be corrected?

Answer 1

[KL]

Your condition div >= i && div < i + 1 probably never becomes true and so class_pointb is never defined. This is why initializing is good (with a zero maybe) and then you'll have to handle this value inside your count_edge function.

Answer 2

[Jan]

You can check this by using the debugger: https://www.mathworks.com/help/matlab/matlab_prog/debugging-process-and-features.html . Set a breakpoint in "class_pointa = i;" line and run the code again. You will see, that the condition is not met, as K L has explained already.

Using the debugger to examine code is essential for programming. It is even more efficient than asking the forum.

By the way: The loop might be less efficient then a vectorized approach:

%  for i = 1:10
%      if div >= i && div < i + 1
%         class_pointa = i;
%          break
%      end
%  end

% This can reply [] !!!
class_pointa = floor(div(div >=1 & div < 11));