title: MATLAB Error using importdata
body: <p>I get an error at the importdata line saying</p>
  
  <p>"Error using importdata (line 137)
  Unable to open file."</p>
  
  <p>when I write in 'specimenAl.dat' manually into the function, the program runs fine. How can I make use of the importarray function while defining the argument as an element of an array?</p>
  
  <pre><code>material = {('specimenAl.dat'), ('specimenSt.dat')};
  A     = importdata(material(1));
  Data  = A.data;
  Force = Data (:,2);
  Displacement = Data (:,1);
  Strain = Data (:,3);
  </code></pre>