MATLAB: Using AND Operator in “if” statements

conditional andif statementMATLAB

Hi,
When I type the following code:
if size([1 2 3])==size([4 5 6]) & size([4 5 6])==size([7 8 9])
    'yes'
else
    'no'
end
MATLAB Code Analyzer issues this warning message: "When both arguments are numeric scalars, consider replacing & with && for performance."
So, I use && instead of &:
if size([1 2 3])==size([4 5 6]) && size([4 5 6])==size([7 8 9])
    'yes'
else
    'no'
end
But when I run the updated script, MATLAB displays an error message in the Command Window: 
??? Operands to the || and && operators must be convertible to logical scalar values.
What can I do to fix this? Thanks in advance.
Andrew DeYoung
Carnegie Mellon University

Best Answer

The problem is that size returns a vector:
size([1 2 3])
ans =
     1     3
Instead, use numel:
if numel([1 2 3])==numel([4 5 6]) && numel([4 5 6])==numel([7 8 9])
  disp('yes')
else
  disp('no')
end
Or you could use all(size([1 2 3])==size([4 5 6]) etc.
I have also put in the disp commands to take care of the other warnings.
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