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|    sci.math.symbolic    |    Symbolic algebra discussion    |    10,432 messages    |
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|    Message 9,376 of 10,432    |
|    Richard Fateman to All    |
|    Re: The Risch algorithm    |
|    16 Apr 17 12:02:13    |
      From: fateman@cs.berkeley.edu              Just to point out (again) that this discussion has rather       broader implications than integration, specifically.              If you just type log(x^2) into Maxima, you get 2*log(x).              If you want to inhibit that transformation, you       must change the (default) setting by logexpand:false.              There are commands integrate(..)       and risch(...) in Maxima.              if logexpand:false, then integrate() produces the       "approved" answer involving log(x^2).               risch() produces the one you don't like,       because it sets up a differential field and to do so it       uses parts of the radcan() program.              This is useful (essential in general) to detect       the dependency of the differential-algebraic extensions       log(x) and log(x^2) =[sometimes] 2*log(x).              As another example, entirely separate from integration,       radcan(log(x^2-1)-log(x+1)) returns log(x-1).              The behavior of the input and output expressions analytically       is different. e.g. at x=-1.              This is entirely deliberate.              RJF              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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