home bbs files messages ]

Forums before death by AOL, social media and spammers... "We can't have nice things"

   sci.math.symbolic      Symbolic algebra discussion      10,432 messages   

[   << oldest   |   < older   |   list   |   newer >   |   newest >>   ]

   Message 9,317 of 10,432   
   clicliclic@freenet.de to clicliclic@freenet.de   
   Re: The leaner and meaner Rubi 4.11 now    
   29 Mar 17 10:22:05   
   
   clicliclic@freenet.de schrieb:   
   >   
   > "Nasser M. Abbasi" schrieb:   
   > >   
   > > I have translated Timofeev to sympy, and I can run the integrals now   
   > > via sympy.   
   > >   
   > > But there were many many changes needed. Not only that, I just found   
   > > that sympy changes all exact numbers to floating point. For example:   
   > >   
   > > >python   
   > > >>> from sympy import *   
   > > >>> x=symbols('x')   
   > > >>> integrate(1/4/sin(1/3*x),x)   
   > >   
   > > 0.375*log(cos(0.333333333333333*x) - 1) -   
   > > 0.375*log(cos(0.333333333333333*x) + 1)   
   > >   
   > > The above is #4 in Timofeev. Notice how the output is all   
   > > decimal. It turns out, one has to tell sympy not to do this   
   > > by changing the input to   
   > >   
   > > >>> integrate(S('1/4')/sin(S('1/3')*x),x)   
   > >   
   > >      3*log(cos(x/3) - 1)/8 - 3*log(cos(x/3) + 1)/8   
   > >   
   > > So, unless there is a way to tell sympy not to change exact   
   > > numbers to floating point number, I would have to do change   
   > > each number n in the test file to become S('n')?  63,000   
   > > integrals?  Not practical.   
   > >   
   > > Will try to ask if there is an option to sympy, so that it   
   > > will do this automatically. This is very strange for a computer   
   > > algebra system to do this.   
   > >   
   >   
   > Or perhaps run:   
   >   
   > integrate(sympify("integrate(1/4/sin(1/3*x),x)"),x)   
   >   
   > The definition of symbols may be unnecessary then.   
   >   
      
   This should have been:   
      
   sympify("integrate(1/4/sin(1/3*x),x)")   
      
   Martin :).   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

[   << oldest   |   < older   |   list   |   newer >   |   newest >>   ]


(c) 1994,  bbs@darkrealms.ca