begin{figure}[h!]
centering
begin{subfigure}[b]
$begin{bmatrix}
w_{1,1}   & w_{1,2}   & cdots & w_{1,m-1}   & w_{1,m}\
w_{2,1}   & w_{2,2}   & cdots & w_{2,m-1}   & w_{2,m}\
vdots    & vdots    & ddots & vdots      & vdots\
w_{n-1,1} & w_{n-1,2} & cdots & w_{n-1,m-1} & w_{n-1,m}\
w_{n,1}   & w_{n,2}   & cdots & w_{n,m-1}   & w_{n,m}\
end{bmatrix}$
label{fig:weight-mat}
end{subfigure}
begin{subfigure}[b]
$begin{bmatrix}
b_{1}\
b_{2}\
vdots\
b_{n-1}\
b_{n}\
end{bmatrix}$
label{fig:bias-vec}
end{subfigure}
caption[Example Connection Weight Matrix with Bias Vector]{Example
         connection weight matrix with bias vector - the network
         represented has $m$ input units and $n$ output units.}
end{figure}

[15] [16]
! Missing number, treated as zero.
<to be read again>
                   $
l.17 $
      begin{bmatrix}