Re: NIntegrate Confusion
- To: mathgroup at smc.vnet.net
- Subject: [mg109161] Re: NIntegrate Confusion
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Wed, 14 Apr 2010 23:12:19 -0400 (EDT)
M = 50;
f[t_] = 100 Sin[5 t];
basis = Table[Sin[n t], {n, 1, M}];
Do it exactly
coef = 2/Pi*Table[
Integrate[f[t] Sin[n t], {t, 0, Pi}],
{n, 1, M}]
{0,0,0,0,100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
coef = 2/Pi*Table[
NIntegrate[f[t] Sin[n t], {t, 0, Pi}],
{n, 1, M}] // Quiet // Chop
{0,0,0,0,100.,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
% == %%
True
Bob Hanlon
---- sukhrob <suhrob84 at bk.ru> wrote:
=============
Hi everybody,
I'm using Mathematica 7.0 , i would like integrate numerically something
like Fourier coefficients, my programe code contains:
M = 50; f[t_] = 100 Sin[5 t];
basis = Table[Sin[n t], {n, 1, M}];
coef = 2/Pi*Table[NIntegrate[f[t] Sin[n t], {t, 0, Pi}], {n, 1, M}]
in result it gives :
NIntegrate::ncvb: NIntegrate failed to converge to prescribed accuracy after
9 recursive bisections in t near {t} = {2.47283}. NIntegrate obtained
-3.88578*10^-15 and 7.654706546923104`*^-15 for the integral and error
estimates. >>
NIntegrate::ncvb: NIntegrate failed to converge to prescribed accuracy after
9 recursive bisections in t near {t} = {2.47283}. NIntegrate obtained
-3.19189*10^-15 and 1.8799124112361456`*^-14 for the integral and error
estimates. >>
NIntegrate::ncvb: NIntegrate failed to converge to prescribed accuracy after
9 recursive bisections in t near {t} = {0.00254055}. NIntegrate obtained
1.2045919817182948`*^-14 and 9.105942246869344`*^-13 for the integral and
error estimates. >>
General::stop: Further output of NIntegrate::ncvb will be suppressed during
this calculation. >>
Can anyone help me to solve that problem. Any help would be very much
appreciated.
Thanks in advance
Sukhrob
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