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 Author Comment/Response Oleg Urminsky 03/08/02 1:57pm I am trying to solve several systems of equations with exponential parameters. The problem is that some of them can be solved with a Log transform, but neither Solve or Reduce finds those solutions. As an example: In[482]:= Solve [{ d1==k*x1^s, d2==k*x2^s}, {k, s}] Out[482]= {} No solution is found. I know, however, that there is a solution if you take the Log of both sides: In[483]:= Solve [{ Log[d1]==Log[k*x1^s],Log[d2]==Log[k*x2^s]}, {k, s}]) Out[483]= {} It still finds no solution. The only way I could get it to work was to use PowerExpand: In[484]:= Solve[{ Log[d1]==PowerExpand[Log[k*x1^s]], Log[d2]==PowerExpand[Log[k*x2^s]]}, {k, s}] Out[484]= s=(-Log[d1] + Log[d2])/(-Log[x1] + Log[x2]), k=[ExponentialE]^\(\(Log[d2]\ Log[x1] - Log[d1]\ \ Log[x2]\)\/\(Log[x1] - Log[x2]\)\)}}\) I had the same problem with Reduce. Here's my question. Is there another routine I could use that will attempt log transforms in searching for a solution? Or would it make a difference if I restricted values to the reals, and can I do that in Solve or Reduce? I can of course try each equation both ways: directly and forcing the log transform, but I wanted to know if there was a better way. Thanks, Oleg URL: ,

 Subject (listing for 'Solve and Log transforms') Author Date Posted Solve and Log transforms Oleg Urminsky 03/08/02 1:57pm Re: Solve and Log transforms Forum Modera... 04/06/02 12:58pm
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