title: illegal plot error when trying to use subplot
body: <p>I am trying to use subplot, but got an error message I do not know how to correct.</p>
  
  <p>(Also, since only the value of w varies, is there a more compact way to write this code rather than saying "cos(stuff*t") ten times in a row? Thanks.)</p>
  
  <p>my current code is</p>
  
  <pre><code>clear all
  clc
  
  t = 0:0.001:40;
  % there are 10 values of w to show, so make a 2x5 grid to show them all via
  % subplot (2,5, blank)
  
  x1=cos(pi/16*t);
  x2=cos(pi/8*t);
  x3=cos(pi/4*t);
  x4=cos(pi/2*t);
  x5=cos(pi*t);
  x6=cos(15*pi/8*t);
  x7=cos(2*pi*t);
  x8=cos(5*pi/2*t);
  x9=cos(3*pi*t);
  x10=cos(4*pi*t);
  
  subplot(2,5,x1), plot(t,x,1), subplot(2,5,x2), plot(t,x,2), subplot(2,5,x3), 
  plot(t,x,3), subplot(2,5,x4), plot(t,x,4), subplot(2,5,x5), plot(t,x,5), 
  subplot(2,5,x6), plot(t,x,6), subplot(2,5,x7), plot(t,x,7), subplot(2,5,x8), 
  plot(t,x,8), subplot(2,5,x9), plot(t,x,9), subplot(2,5,x10), plot(t,x,10);
  
  
  
  %Error using subplot (line 330);
  
  %Illegal plot number;
  
  %Error in (line 19);
  %subplot(2,5,x1), plot(t,x,1);
  </code></pre>