About logical calculation. Is this a bug?

what happened to this case? Is this a matlab bug?

[Jingli Xie]

logical should be 1 at the lower left corner of the picture.

-1<p_grad == 1, p_grad < 1 ==1, bug -1<p_grad<1 == 0

Answer 1

[Adam Danz]

The operation

p_grad = 1.1200e-17; 
-1 < p_grad < 1

works from left-to-right. It is interpretted as

p_grad = 1.1200e-17; 
(-1 < p_grad)  <  1

which is simplified to

1  <  1

which equals 0 (false).

To determine if p_grad is between -1 and 1, (parentheses optional)

(-1 < p_grad)  &&  (p_grad < 1)      % for scalar values
(-1 < p_grad)  &  (p_grad < 1)       % for non-scalar values or when
                                     % number of element is unknown

[Jingli Xie]

Oh. I see. Thank you.

[Stephen23]

Also note that the A<B<C syntax does not exist in the MATLAB documentation:

https://www.mathworks.com/help/matlab/logical-operations.html

https://www.mathworks.com/help/matlab/matlab_prog/operator-precedence.html

[Steven Lord]

If I remember correctly, as of release R2019b if you try to use that idiom in a file in the Editor Code Analyzer will warn you that it doesn't do what you think it does.