title: MATLAB Convert cell to double and concatenate or reshape into one column
body: <p>I have lat and lon as cells of size 1x7 (in which inside each cell, the cell is a column with varying numbers of rows). I want to convert each of the 7 columns to double and then concatenate them into a column so that I have a matrix of size 216x1.</p>
  
  <p>For example (shortened version), if </p>
  
  <pre><code> lat{1,1}
  '40.400959'
  '40.695078'
  '40.969112'
  '41.264171'
  '41.400968'
  '41.517772'
  '41.530011'
  '41.550005'
  '41.583183'
  '41.603159'
  
   lat{1,2}
  '38.082155'
  '38.176278'
  '38.529631'
  '38.612034'
  '38.700632'
  </code></pre>
  
  <p>Then, I want to have, in double form:
      40.400959
      40.695078
      40.969112
      41.264171
      41.400968
      41.517772
      41.530011
      41.550005
      41.583183
      41.603159
      38.082155
      38.176278
      38.529631
      38.612034
      38.700632</p>
  
  <p>I managed to convert to double, but I'm not sure how to do the concatenate (or reshape) to column part.</p>
  
  <pre><code>for i = 1:7
      lat = str2double(lat_PM25{i});
      lon = str2double(lon_PM25{i});
  end
  </code></pre>