title: assertion failed (a_size.width == len) in cv::gemm
body: <pre><code>#include &lt;opencv2\core\core.hpp&gt;
  #include&lt;opencv2\imgproc\imgproc.hpp&gt;
  #include&lt;opencv2\highgui\highgui.hpp&gt;
  #include &lt;iostream&gt;
  #include&lt;conio.h&gt;
  
  using namespace cv;
  using namespace std;
  
  int main()
  {
  Mat im= imread("D:\\try.jpg"),newface,A;
  Mat im2 = imread("D:\\project\\barc\\variables\\Eigenface.jpg");
  
  cvtColor(im, im, CV_BGR2GRAY);
  cvtColor(im2, im2, CV_BGR2GRAY);
  
  resize(im, im, Size(48, 48));
  newface = im.reshape(0, 2304);
  
  newface.convertTo(newface, CV_32FC1);
  im2.convertTo(im2, CV_32FC1);
  
  cout &lt;&lt; "Diff : " &lt;&lt; newface.size() &lt;&lt; "\t" &lt;&lt; "channels" &lt;&lt; newface.channels() &lt;&lt;  endl;
  cout &lt;&lt; "Eigen : " &lt;&lt; im2.size() &lt;&lt; "\t" &lt;&lt; "channels" &lt;&lt; im2.channels() &lt;&lt; endl;
  
  A = im2*newface.t();
  
  _getch();
  
  return 0;
  }
  </code></pre>
  
  <p>The Eigenface.jpg is of dimension (9x2304). When i am multiplying with the image i am facing this error is coming can anyone help?</p>