Sum and NSum:how can I say for mathematica when stop the Sum?
- To: mathgroup@smc.vnet.net
- Subject: [mg11706] Sum and NSum:how can I say for mathematica when stop the Sum?
- From: Fernando Marcos Santana Barreto <barreto@fec.unicamp.br>
- Date: Sat, 21 Mar 1998 18:35:48 -0500
---------- Forwarded message ---------- From: Fernando Marcos Santana
Barreto <barreto@fec.unicamp.br> To: mathgroup@smc.vnet.net
Hello, Tom
I am development my reseach slowly, but I am developmet.
I am using senos and cossenos Sum's
I have a sum, but I don't know how much terms of the sum I need use ,
and I cant written:
In[9]:=
w1[x_, y_] := 4*qo*a^4/d*Sum[g1[y]*ff[x], {m, 1, Infinity, 2}];
because this way the Mathematica will expend a long time for give-me
the output , so a did
In[5]:=
ff[x_] := Sin[m*Pi*x/a]
g1[y_] = (4*a + 2*m*Pi*y*Sech[(b*m*Pi)/(2*a)]*
Sinh[(m*Pi*y)/a] - Cosh[(m*Pi*y)/a]*Sech[(b*m*Pi)/(2*a)]*
(4*a + b*m*Pi*Tanh[(b*m*Pi)/(2*a)]))/(4*a*m^5*Pi^5)
t=9;
w1[x_, y_] := 4*qo*a^4/d*Sum[g1[y]*ff[x], {m, 1, t, 2}];
but I am not sure that 9 will give-me the answer which suficiently
acurecy
I want to get the answer which precision about 10^-4 for exemplo
how can I tell the Mathematica about it?
Shoud I use Nsum ? and put numerical values for my variables?
But using NSum, I need enter whith inicial and last term of the sum.
I read the help about sum and Nsum but did'd can solve my problem
I am waiting for your help
best wishes
Fernando