How to append NaN to a matrix of 1 row and 1683 columns?

I have a matrix of 1 row and 1683 columns, I want to append NaN at the end of this matrix so that it can be equal to 1686 columns. I have another matrix of 1 * 1686. Once they both will be equal, I have to apply confusion matrix. Any help in this case will be highly appreciated. Thanks in advance.

Answer 1

[Walter Roberson]

YourMatrx(1684:1686) = NaN;

[SUKHRAJ KAUR]

thanku sooo much.