# Which is the “correct” way to represent C=AB with \mathbf?

Which is the "correct" way to represent C=AB with \mathbf?

\mathbf{C=AB} or \mathbf{C}=\mathbf{AB} or \mathbf{C}=\mathbf{A}\mathbf{B}

• Probably \mathbf{C}=\mathbf{A}\mathbf{B}, given that A and B are separate symbols. – Henri Menke Dec 2 '18 at 3:51
• I guess that the correct way is the way you like, I personally never use \mathbf, but \boldsymbol instead, and I put \, between the symbols. I am aware that several users disagree, but I do not think they can call my way of doing thins "wrong". In the end you will never be able to really clarify if, say, typesetting differential ds upright (what I do) right or wrong. But I agree with @HenriMenke that \mathbf{A}\mathbf{B} is better, at the very least you can search for these symbols more easily in your source code. – user121799 Dec 2 '18 at 4:20

I would suggest not to use \mathbf explicitly. It would be better to define some meaningful macro name like \newcommand\matr[1]{\mathbf{#1}} and use it throughout the document. This way the source code becomes more readable and you get the easy way of changing the definition if desired. As for \matr{A}\matr{B} vs \matr{AB}, I'd say that the former would be better unless AB denotes a single matrix (which is very unusual in math).