From: nma@12000.org   
      
   On 1/29/2017 9:18 PM, oldk1331@gmail.com wrote:   
      
   > Hi Martin, FriCAS does an extra simplification, causes the result to be   
   > discontinuous at x=0.  This is caused by the same bug you mentioned   
   > in the previous thread.  I think there is a good enough fix, and the   
   > result after patching this bug is continuous:   
   >   
   > (log((2*x*((-1)*x^4+1)^(1/2)+((-1)*x^4+2*x^2+1))/(x^4+1))+2*atan((x^2*((-1)*   
   >   x^4+1)^(1/2)+(x^3+x))/(((-1)*x^4+1)^(1/2)+((-1)*x^3+x))))/4   
   >   
      
   Hi,   
      
   When you say it is continuous, is there an implied interval   
   associated with this?   
      
   I am asking, since there are singularities at x=+- 1 in   
   the above expression.   
      
   r:=(log((2*x*((-1)*x^4+1)^(1/2)+((-1)*x^4+2*x^2+1))/(x^4+1))+2*a   
   ctan((x^2*((-1)*   
      x^4+1)^(1/2)+(x^3+x))/(((-1)*x^4+1)^(1/2)+((-1)*x^3+x))))/4;   
      
   singular(r,x);   
      
   {x = -1}, {x = 1},   
   {x = -(1/2)*sqrt(2)-(1/2*I)*sqrt(2)},   
   {x = -(1/2)*sqrt(2)+(1/2*I)*sqrt(2)},   
   {x = (1/2)*sqrt(2)-(1/2*I)*sqrt(2)},   
   {x = (1/2)*sqrt(2)+(1/2*I)*sqrt(2)}   
      
   subs(x=1,r);   
   Error, numeric exception: division by zero   
   subs(x=-1,r);   
   Error, numeric exception: division by zero   
      
      
   So I assume, the range where it is continuous is meant   
   to be from [-1,1] only?  Sorry if this meant to be, I did   
   not follow all of the thread before.   
      
   Thanks,   
   --Nasser   
      
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