This error happens because the inputs to strcmp are incompatible sizes.
Example 1: both inputs the same size (works):
a = {'baba', 'booey'};
b = {'barbara', 'booey'};
strcmp(a,b) % works
Example 2: one input a scalar, one non-scalar (works):
a = {'baba'};
b = {'barbara', 'booey'};
strcmp(a,b) % works
Example 3: non-scalar inputs of different sizes (error):
a = {'baba', 'booey', 'mountain'};
b = {'barbara', 'booey'};
strcmp(a,b) % error
This means that, in your case, gTruthClassNames and detectorClassNames are non-scalars with different sizes. I'm not able to say why that is or what you should do about it though.
