Thanks for your answer. But, I still don't know how I can deal with this error.
Anyway, Thank you very much. Kyusik. 2016년 9월 5일 월요일 오후 9시 47분 21초 UTC+9, Wolfgang Bangerth 님의 말: > > On 09/05/2016 06:04 AM, hank...@gmail.com <javascript:> wrote: > > > > K_Inv[0][0]=2*r/(cos(theta)*cos(theta)), > > K_Inv[1][1]=2*r/(sin(theta)*sin(theta)), K_Inv[2][2]=r > > > > r is calculated by "r=sqrt(x^2+y^2) ", and theta is calculated by > "theta=x/y" > > > > But, as you can expect that ,on the points where |x|<0.0000001 or > > |y|<0.000001, cos(theta) or sin(theta) is almost zero. So, It seems > that It > > causes the singularity. > > > > So, At first I tried to change the above 2 element in K_Inv like this... > > > > K_Inv[0][0]=2*r/(cos(theta)*cos(theta)+del) > > K_Inv[1][1]=2*r/(sin(theta)*sin(theta)+del), > > Instead of this approach, you should use the following: if r>delta, use > the > formula above. If r<=delta, use l'Hopital's rule to get an expression that > avoids the division by zero. > > That said, you still have a problem for those values of x,y where theta is > close to zero or one, but r is not. For example, for x=0, y=1, you have > r=1 > theta=pi/2 > cos(theta)=0 > K_inv[0,0] = 2/0 > You need to think about what you want to do with this situation. > > Best > W. > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: bang...@colostate.edu > <javascript:> > www: http://www.math.colostate.edu/~bangerth/ > > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
