After reading this post in the CVX forum, I also came to the conclusion that there might be a problem related to the CVX vec function.
I have reordered my search path so that the CVX references are at the top of the list. Thus, when I type the command
which -all vec
the output is
C:\Users\Garrett\Dropbox (MIT)\Research\Code\CVX_2.1\cvx-w64\cvx\functions\@cvx\vec.m % cvx method
C:\Users\Garrett\Dropbox (MIT)\Research\Code\YALMIP\YALMIP\yalmip\@sdpvar\vec.m % sdpvar method
C:\Users\Garrett\Dropbox (MIT)\Research\Code\YALMIP\YALMIP\yalmip\extras\@ndsdpvar\vec.m % ndsdpvar method
I still get the error
Undefined function 'vec' for input arguments of type 'double'.
Update
When I manually added the path to the
cvx/functions/vec_
directory described in this post, the problem went away! Thanks for sticking with me, Mark! 