Logical Input for embedded if loop.

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Andrew Hawkins 2017-5-30

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/342541-logical-input-for-embedded-if-loop

编辑： Guruprasad Madhale Jadav 2018-6-6

Below is the assignment: 1. Create a 4 x 8 matrix of randomly generated numbers. 2. Loop through all rows and columns, and test whether each element is greater than 0.5. 3. Report the results of the test along with the value of the matrix ele- ment and its row-column position. For example, your Matlab script should print The 3rd row and 8th column has a value of 0.42345 and is not bigger than 0.5. 4. Make sure to add exceptions to print out 1st, 2nd, and 3rd, instead of 1th, 2th, and 3th. 5. Put this code into a separate function that you can call from the com- mand line with two inputs, corresponding to the number of rows and the number of columns of the matrix.

The following code has an issue in the if loop where it states that the input and output for a logical comparator are not balanced. However, I have added 1 one on each side. A troubleshoot would be appreciated

%4.7 Excercises Cohen text
rand_matrix_A = rand ([4,8]);
[row,col,v] = find (rand_matrix_A > 0.5);
ind_row_col= horzcat (row, col);
for i = 1 : size (ind_row_col, 1);
% exceptions for row index  
 if ind_row_col(i,1)== 1 or ind_row_col(i,2)== 1;
     num_modifier1  = 'st';
disp (['The '  num2str(ind_row_col(i,1)) num_modifier1  ' row and '   num2str(ind_row_col (i, 2)) num_modifier1  ' column has a value of '  num2str(rand_matrix_A (ind_row_col(i,1), ind_row_col (i, 2)))  ' and is not bigger than 0.5'])
end 
if ind_row_col(i,1)== 2  or ind_row_col(i,2) == 2;
     num_modifier2  = 'nd';
disp (['The '  num2str(ind_row_col(i,1)) num_modifier2  ' row and '   num2str(ind_row_col (i, 2)) num_modifier2  ' column has a value of '  num2str(rand_matrix_A (ind_row_col(i,1), ind_row_col (i, 2)))  ' and is not bigger than 0.5'])
      end 
if ind_row_col(i,1)== 3 or ind_row_col(i,2) == 3;
     num_modifier3  = 'rd';
disp (['The '  num2str(ind_row_col(i,1)) num_modifier3  ' row and '   num2str(ind_row_col (i, 2)) num_modifier3  ' column has a value of '  num2str(rand_matrix_A (ind_row_col(i,1), ind_row_col (i, 2)))  ' and is not bigger than 0.5'])
      end 
disp (['The '  num2str(ind_row_col(i,1)) 'th row and '   num2str(ind_row_col (i, 2)) 'th column has a value of '  num2str(rand_matrix_A (ind_row_col(i,1), ind_row_col (i, 2)))  ' and is not bigger than 0.5'])
end

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Answer 1

Jan 2017-5-30

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/342541-logical-input-for-embedded-if-loop#answer_268949

编辑：Jan 2017-5-30

在 MATLAB Online 中打开

The or() command is used incorrectly:

if ind_row_col(i,1) == 1 or ind_row_col(i,2) == 1;

Better:

if ind_row_col(i,1) == 1 || ind_row_col(i,2) == 1

or

if or(ind_row_col(i,1) == 1, ind_row_col(i,2) == 1)

or leaner:

if any(ind_row_col(i,1:2) == 1)

(You see: no trailing semicolon)

There are no "if loops", neither in Matlab nor in any otehr programming language.

input and output for a logical comparator are not balanced

Better post a complete copy of the message. A rough rephrasing does not allow to understand, what you see. Perhaps this message means, that the indentation is poor. This is a hint only and not an error. Mark the code an hit Ctrl-I. Does the warning disappear?

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Andrew Hawkins 2017-5-30

在 MATLAB Online 中打开

I received the following message despite the edit you described above. I may have mistaken the error in my original post.

Error using  | 
Too many input arguments.

Jan 2017-5-31

编辑：Jan 2017-5-31

Please post the complete error message and show us the failing line of code. The code you have posted does not contain a | , so how could we guess, what's going on?

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