Re: damped oscilations data fit

• To: mathgroup at smc.vnet.net
• Subject: [mg70556] Re: [mg70491] damped oscilations data fit
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Thu, 19 Oct 2006 03:23:18 -0400 (EDT)

data={{0,54},{120,56.5},{230,56},
{305,54},{340,53},{360,52.7},
{378,52.5},{405,52.5},{443,53},
{480,53.5},{510,54},{540,54.7},
{570,54.4},{602,56},{643,56.5},
{660,56.5},{685,56.25},{706,56},
{727,55.25},{743,55.5},{756,55.25},
{775,55},{787,54.75},{799,54.5},
{814,54.25},{828,54},{845,53.75},
{858,53.5},{877,53.25},{894,53},
{923,52},{951,53},{983,53.5},
{1014,54}};

expr= a*Sin[b*x+c]+d;

f[x_] = expr/.
FindFit[data, expr, {a, {b, Pi/250}, c, d}, x]

54.53877662098067 - 1.8267292955289056*
Sin[0.2755009270530187 - 0.01221727723631315*x]

Plot[f[x], {x, -80, 1050}, PlotStyle -> Blue,
Epilog ->
{Red, AbsolutePointSize[4], Point /@ data}];

Bob Hanlon

---- "Miroslav HÃ½Å¾a" <mirek.hyza at gmail.com> wrote:
> hello,
> I have one question about data manipulation in mathematica.
> I've got set of experimental data. Data describe damped oscillation. My question is following:
>
> How can I fit these data?
> I would like to get formula of function which will approximately describe my data and plot this function.
>
> my data list:
> {{0, 54}, {120, 56.5}, {230, 56}, {305, 54}, {340, 53}, {360, 52.7}, {378, 52.5}, {405, 52.5}, {443, 53}, {480, 53.5}, {510, 54}, {540, 54.7}, {570, 54.4}, {602, 56}, {643,56.5}, {660, 56.5}, {685, 56.25}, {706, 56}, {727, 55.25}, {743, 55.5}, {756, 55.25}, {775, 55}, {787, 54.75}, {799, 54.5}, {814, 54.25}, {828, 54}, {845, 53.75}, {858, 53.5}, {877, 53.25}, {894, 53}, {923, 52}, {951, 53}, {983, 53.5}, {1014, 54}}
>
> Have anyone an idea?
> I'm mathematica beginner therefore I'll be grateful for any suggestion.
> Thanks
> <<mira
>

--

Bob Hanlon
hanlonr at cox.net

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