Executing the body of IF statement.

Hi,

Why MATLAB is not executing the body of the following selection if statement eventhough I believe the condition is true? Your help would be appreciated!

Note: members is a 1by 3 cell. attack = 5, n1=7

for ii=1:n1   % Check if neighboring nodes will survive the cascading failure or not
   if  ~ismember(ii,members{1}) && ~ii==attack
       A(ii,:)=0;
       A(:,ii)=0;
       C(ii,:)=0; % All nodes in Layer B coupled to neighboring nodes will get failed
       C(:,ii)=0;
   end
 end

[Ameer Hamza]

Unfortunately, believing is not enough. Add breakpoint at the line of if statement and check why the condition remains false. https://www.mathworks.com/help/matlab/matlab_prog/set-breakpoints.html

[Waseem AL Aqqad]

This is what I did actually before posting this question

[Waseem AL Aqqad]

But thanks for sharing that useful page.

Answer 1

[Stephen23]

Solution: the logic is incorrect:

~ii==attack

should be

ii~=attack

Explanation: the code

~ii==attack

following the rules of operator precedence is equivalant to

(~ii)==attack

which for the case that both ii and attack are non-zero is equivalent to

false==true

which is thus simply equivalent to

false

[Waseem AL Aqqad]

Thank you very much, Stephen!

[Waseem AL Aqqad]

Thanks for the explanation.