From: Albert_Rich@msn.com   
      
   On Saturday, April 15, 2017 at 4:52:35 PM UTC-10, Albert Rich wrote:   
   >    
   > log(z^2) is not equal to 2*log(z) over half the complex plane.     
   >    
   > It seems to me if indeed the Risch Algorithm cannot be trusted to produce   
   analytically valid antiderivatives over the complex plane, a computer algebra   
   system's Integrate command should first try using elementary methods that do.   
   Then iff that fails,    
   resort to the Risch Algorithm AND warn users the result may not be valid over   
   the complex plane.   
   >    
   > As Rubi demonstrates, rule-based elementary methods can produce optimal,   
   analytically valid antiderivatives for a large class of integrands.   
   >    
   > Albert   
      
   I amend the last sentence of my recommendation to read:  Then iff that fails,   
   resort to the Risch Algorithm AND attempt to validate that result by   
   differentiation.  If validation fails, warn users the result may not be valid   
   over the complex plane.   
       
   Albert   
      
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