Question: Fit a Curve to Data

Hi,

I have some data (points of results -> a list of x - data and a list of corresponding y - data) and I would like to fit a curve to this data.  curves does not fit very well to the data points.

Can anybody give me a method to fit a curve to the data?

Tanks!

The data are:

xdata:=[1.131744108, 1.142949495, 1.154154883, 1.165360270, 1.176565657, 1.187771044, 1.198976431, 1.210181819, 1.221387206, 1.232592593, 1.243797980, 1.255003368, 1.266208755, 1.277414142, 1.288619529, 1.299824916, 1.311030304, 1.322235691, 1.333441078, 1.344646465, 1.355851852, 1.367057240, 1.378262627, 1.389468014, 1.400673401, 1.411878788, 1.423084176, 1.434289563, 1.445494950, 1.456700337, 1.467905725, 1.479111112, 1.490316499, 1.501521886, 1.512727273, 1.523932661, 1.535138048, 1.546343435, 1.557548822, 1.568754209, 1.579959597, 1.591164984, 1.602370371, 1.613575758, 1.624781145, 1.635986533, 1.647191920, 1.658397307, 1.669602694, 1.680808082, 1.692013469, 1.703218856, 1.714424243, 1.725629630, 1.736835018, 1.748040405, 1.759245792, 1.770451179, 1.781656566, 1.792861954, 1.804067341, 1.815272728, 1.826478115, 1.837683502, 1.848888890, 1.860094277, 1.871299664, 1.882505051, 1.893710438, 1.904915826, 1.916121213, 1.927326600, 1.938531987, 1.949737375, 1.960942762, 1.972148149, 1.983353536, 1.994558923, 2.005764311, 2.016969698, 2.028175085, 2.039380472, 2.050585859, 2.061791247, 2.072996634, 2.084202021, 2.095407408, 2.106612795, 2.117818183, 2.129023570, 2.140228957, 2.151434344, 2.162639732, 2.173845119, 2.185050506, 2.196255893, 2.207461280, 2.218666668, 2.229872055, 2.241077442, 2.252282829, 2.263488216, 2.274693604, 2.285898991, 2.297104378, 2.308309765, 2.319515152, 2.330720540, 2.341925927, 2.353131314, 2.364336701, 2.375542089, 2.386747476, 2.397952863, 2.409158250, 2.420363637, 2.431569025, 2.442774412, 2.453979799, 2.465185186, 2.476390573, 2.487595961, 2.498801348, 2.510006735, 2.521212122, 2.532417509, 2.543622897, 2.554828284, 2.566033671, 2.577239058, 2.588444446, 2.599649833, 2.610855220, 2.622060607, 2.633265994, 2.644471382, 2.655676769, 2.666882156, 2.678087543, 2.689292930, 2.700498318, 2.711703705, 2.722909092, 2.734114479, 2.745319866, 2.756525254, 2.767730641, 2.778936028, 2.790141415, 2.801346802, 2.812552190, 2.823757577, 2.834962964, 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6.297427612, 6.308632999, 6.319838386, 6.331043774, 6.342249161, 6.353454548, 6.364659935, 6.375865322, 6.387070710, 6.398276097, 6.409481484, 6.420686871, 6.431892259, 6.443097646, 6.454303033, 6.465508420, 6.476713807, 6.487919195, 6.499124582, 6.510329969, 6.521535356, 6.532740743, 6.543946131, 6.555151518, 6.566356905, 6.577562292, 6.588767679, 6.599973067, 6.611178454, 6.622383841, 6.633589228, 6.644794616, 6.656000003, 6.667205390, 6.678410777, 6.689616164, 6.700821552, 6.712026939, 6.723232326, 6.734437713, 6.745643100, 6.756848488, 6.768053875, 6.779259262, 6.790464649, 6.801670036, 6.812875424, 6.824080811, 6.835286198, 6.846491585, 6.857696973, 6.868902360, 6.880107747, 6.891313134, 6.902518521, 6.913723909, 6.924929296, 6.936134683, 6.947340070, 6.958545457, 6.969750845, 6.980956232, 6.992161619, 7.003367006, 7.014572393, 7.025777781, 7.036983168, 7.048188555, 7.059393942, 7.070599330, 7.081804717, 7.093010104, 7.104215491, 7.115420878, 7.126626266, 7.137831653, 7.149037040, 7.160242427, 7.171447814, 7.182653202, 7.193858589, 7.205063976, 7.216269363, 7.227474750, 7.238680138, 7.249885525, 7.261090912, 7.272296299, 7.283501686, 7.294707074, 7.305912461, 7.317117848, 7.328323235, 7.339528623, 7.350734010, 7.361939397, 7.373144784, 7.384350171, 7.395555559, 7.406760946, 7.417966333, 7.429171720, 7.440377107, 7.451582495, 7.462787882, 7.473993269, 7.485198656, 7.496404043, 7.507609431, 7.518814818, 7.530020205, 7.541225592, 7.552430980, 7.563636367, 7.574841754, 7.586047141, 7.597252528, 7.608457916, 7.619663303, 7.630868690, 7.642074077, 7.653279464, 7.664484852, 7.675690239, 7.686895626, 7.698101013, 7.709306400, 7.720511788, 7.731717175, 7.742922562, 7.754127949, 7.765333337, 7.776538724, 7.787744111, 7.798949498, 7.810154885, 7.821360273, 7.832565660, 7.843771047, 7.854976434, 7.866181821, 7.877387209, 7.888592596, 7.899797983, 7.911003370, 7.922208757, 7.933414145, 7.944619532, 7.955824919, 7.967030306, 7.978235694, 7.989441081, 8.000646468, 8.011851855, 8.023057242, 8.034262630, 8.045468017, 8.056673404, 8.067878791, 8.079084178, 8.090289566, 8.101494953, 8.112700340, 8.123905727, 8.135111114, 8.146316502, 8.157521889, 8.168727276, 8.179932663, 8.191138051, 8.202343438, 8.213548825, 8.224754212, 8.235959599, 8.247164987, 8.258370374, 8.269575761, 8.280781148, 8.291986535, 8.303191923, 8.314397310, 8.325602697, 8.336808084, 8.348013471, 8.359218859, 8.370424246, 8.381629633, 8.392835020, 8.404040408, 8.415245795, 8.426451182, 8.437656569, 8.448861956, 8.460067344, 8.471272731, 8.482478118, 8.493683505, 8.504888892, 8.516094280, 8.527299667, 8.538505054, 8.549710441, 8.560915828, 8.572121216, 8.583326603, 8.594531990, 8.605737377, 8.616942764, 8.628148152, 8.639353539, 8.650558926, 8.661764313, 8.672969701, 8.684175088, 8.695380475, 8.706585862, 8.717791249, 8.728996637, 8.740202024, 8.751407411, 8.762612798, 8.773818185, 8.785023573, 8.796228960, 8.807434347, 8.818639734, 8.829845121, 8.841050509, 8.852255896, 8.863461283, 8.874666670, 8.885872058, 8.897077445, 8.908282832, 8.919488219, 8.930693606, 8.941898994, 8.953104381, 8.964309768]

ydata:=[24.39436387, 21.73276252, 20.33797056, 19.16856344, 18.45078452, 17.73146015, 17.15080253, 16.71683581, 16.37243285, 15.93774100, 15.57621164, 15.26412111, 14.98437362, 14.77015050, 14.57773616, 14.40088412, 14.15787900, 13.92049691, 13.73076570, 13.55751470, 13.39640822, 13.24451795, 13.09979357, 12.96837844, 12.86250033, 12.76294094, 12.66862566, 12.57871361, 12.49253735, 12.35921629, 12.22919691, 12.10405528, 11.98658412, 11.89573253, 11.80959312, 11.72744791, 11.64872021, 11.57294124, 11.49972586, 11.42875458, 11.35976014, 11.29251704, 11.22683370, 11.16254634, 11.09951374, 11.03761386, 10.98245340, 10.93779143, 10.89451622, 10.85250737, 10.81165842, 10.77187480, 10.73307231, 10.69334527, 10.63437652, 10.57700009, 10.52105356, 10.46639665, 10.41290769, 10.36048041, 10.30902183, 10.25844991, 10.20869212, 10.15968423, 10.11136881, 10.06369456, 10.01661555, 9.97851621, 9.94583837, 9.91392828, 9.88273418, 9.85220910, 9.82231024, 9.79299853, 9.76423836, 9.73599700, 9.70824446, 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