title: How to create vector of symbolic variables in sympy
body: <p>How to create  vector of symbolic variables in sympy? I want to do something like</p>
  
  <pre><code>x, x1, x2, x3 = symbols ('x x1 x2 x3')
  A = [x+x1,x+x2,x+x3]
  B = A * Transpose(A)
  print (B)
  </code></pre>
  
  <p><code>A</code> is array of symbolic variables. 
  I checked with sympy <a href="http://docs.sympy.org/0.7.2/modules/matrices/expressions.html#module-sympy.matrices.expressions" rel="noreferrer">documentation</a>, but couldn't figure out.</p>
  
  <p>(Python 2.7.6, sympy 0.7.4.1)</p>
  
  <p>Update:</p>
  
  <p>I want to do something like </p>
  
  <pre><code>x, x1, x2, x3 = symbols ('x x1 x2 x3')
  v1e = x+x1
  v2e = x+x2
  v3e = x+x3
  v1 = v1e.subs(x1,1)
  v2 = v2e.subs(x2,2)
  v3 = v3e.subs(x3,3)
  A = Matrix ([v1,v2,v3])
  B = A * Transpose(A)
  print (B)
  </code></pre>
  
  <p>But seems that there is problem with <code>v1,..</code> putting as matrix elements. Any suggestions?</p>