title: Pandas dataframe: multiply row by previous row
body: <p>I have this dataframe as input:                          </p>
  
  <pre><code>                       df1      
                  A       B      C
  20/08/17    0.0000% 0.0000% 0.0000%
  21/08/17    0.0000% 0.0000% 0.0000%
  22/08/17    1.0000% 1.0000% 1.0000%
  23/08/17    0.0000% 0.0000% 0.0000%
  24/08/17    1.9417% 0.9709% 0.9709%
  25/08/17    1.8692% 0.9346% 0.9346%
  </code></pre>
  
  <p>And I am trying to get the following dataframe as output:</p>
  
  <pre><code>                      df2       
                  A       B       C
  20/08/17    0.0000% 0.0000% 0.0000%
  21/08/17    0.0000% 0.0000% 0.0000%
  22/08/17    1.0000% 1.0000% 1.0000%
  23/08/17    1.0000% 1.0000% 1.0000%
  24/08/17    2.9806% 2.0097% 2.0097%
  25/08/17    4.9612% 3.0194% 3.0194%
  </code></pre>
  
  <p>where the value </p>
  
  <pre><code>df2['A'][1]=df2['A'][0]*(1+df1.sum(axis=1))+df1['A'][1]
  </code></pre>
  
  <p>I would like to apply this function to the whole dataframe.</p>
  
  <p>Could you please help me on this?</p>