title: How can I give a number to a symbolic variable in MATLAB?
body: <p>I try to declare a symbolic variable in MATLAB with this code:</p>
  
  <pre><code> syms a;
  </code></pre>
  
  <p>I do my computation on this variable and all thing is fine. But my problem is that, I don't know how can I give a number to variable and get the result as a number. For example the answer of my code is </p>
  
  <pre><code>   answer=exp(-10*a);
  </code></pre>
  
  <p>For instance I want to give 40 to "a" and get the answer as </p>
  
  <pre><code>   answer = 
          1.9152e-174
  </code></pre>
  
  <p>I really appreciate any suggestion.</p>