Undeclared function or variable.

Question

Khushank Singhal 2017-12-17

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/373354-undeclared-function-or-variable

编辑： Jan 2017-12-17

采纳的回答： KL

wire_mesh.m

在 MATLAB Online 中打开

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?

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Answer 1

KL 2017-12-17

1
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https://ww2.mathworks.cn/matlabcentral/answers/373354-undeclared-function-or-variable#answer_296616

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.

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Answer 2

Jan 2017-12-17

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/373354-undeclared-function-or-variable#answer_296621

编辑：Jan 2017-12-17

在 MATLAB Online 中打开

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));