Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parenthe

I need some help to fix my code.

I keep getting error message, but I have not been able to find how I can fix the codes

error message

Invalid expression. Check for missing multiplication operator, missing or unbalanced

delimiters, or other syntax error. To construct matrices, use brackets instead of

parentheses.

my codes

IndexImg((Orientation >= pi/8 & Orientation < pi/4) | (Orientation >= -3pi/4 & Orientation < -5pi/8) & Magnitude >= EdgeThreshold) = 3;

Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses.

EdgeImg((Orientation >= pi/8 & Orientation < pi/4) | (Orientation >= -3pi/4 & Orientation < -5pi/8) & Magnitude >= EdgeThreshold) = Magnitude((Orientation >= pi/8 & Orientation < pi/4) | (Orientation >= -3pi/4 & Orientation < -5pi/8));
% Label = 4 for 135 degree edges
IndexImg((Orientation >= -pi/4 & Orientation < -pi/8) | (Orientation >= 5pi/8 & Orientation <= pi/2) & Magnitude >= EdgeThreshold) = 4;
EdgeImg((Orientation >= -pi/4 & Orientation < -pi/8) | (Orientation >= 5pi/8 & Orientation <= pi/2) & Magnitude >= EdgeThreshold) = Magnitude((Orientation >= -pi/4 & Orientation < -pi/8) | (Orientation >= 5*pi/8 & Orientation <= pi/2));

Answer 1

[Les Beckham]

You are missing the multiplication operator in several places. For example:

IndexImg((Orientation >= pi/8 & Orientation < pi/4) | (Orientation >= -3*pi/4 & Orientation < -5*pi/8) & Magnitude >= EdgeThreshold) = 3;
%                                                                       ^                       ^    

Answer 2

[Walter Roberson]

Orientation >= -3pi/4

MATLAB does not have any implied multiplication. 3pi is invalid in MATLAB.

Side note: I recommend using temporary variables

mask = (Orientation >= pi/8 & Orientation < pi/4) | (Orientation >= -3*pi/4 & Orientation < -5*pi/8) & Magnitude >= EdgeThreshold;
IndexImg(mask) = 3;

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

A|B&C is treated as A|(B&C) not as (A|B)&C .

I recommend that you use () to explicitly indicate the relative order you want for those operations, as readers might well have forgotten the rule.