title: Solving Systems of Equations with SymPy
body: <p>I'm trying to solve a set of equations with SymPy 0.7.1:</p>
  
  <pre><code>from sympy import *
  equations = [
      Eq(S('vf'), S('vi + a*t')),
      Eq(S('d'), S('vi*t + 1/2*a*t**2')),
      Eq(S('a'), S('10')),
      Eq(S('d'), S('60')),
      Eq(S('vi'), S('5'))
  ]
  print solve(equations)
  </code></pre>
  
  <p>produces the correct result, but in a strange order:</p>
  
  <pre><code>[(-4, 10, 60, -35, 5), (3, 10, 60, 35, 5)]
  </code></pre>
  
  <p>How can I identify which value fits which variable?  The variable order seems arbitrary.  <a href="http://docs.sympy.org/0.7.1/modules/solvers/solvers.html" rel="noreferrer">The documentation suggests</a> providing additional arguments:</p>
  
  <pre><code>print solve(equations, var('a'), var('d'), var('t'), var('vi'), var('vf'))
  </code></pre>
  
  <p>But this seems to have no effect.</p>
  
  <p>Thanks in advance for any help!</p>