matlab数据拟合,有图有例子,一看就会

1、Matlab CFTool 使用简介:单一变量的曲线逼近Matlab有一个功能强大的曲线拟合工具箱 cftool，使用方便，能实现多种类型的线性、非线性曲线拟合。下面结合我使用的Matlab R2007b来简单介绍如何使用这个工具箱。假设我们要拟合的函数形式是 y=A*x*x + B*x, 且A>0,B>0。1、在命令行输入数据： x=你的X轴数据;y=你的丫轴数据;cftool可以将上面三个行建立一个M文件，以便后面进行数据拟合时可以直接使用，点 击运行即可进入曲线拟合工具箱界面“ Curve Fitti ng tool ”(1) 点击“ Data”按钮，弹出“ Data”窗口；

2、(2) 利用X data和丫 data的下拉菜单读入数据x,y，可修改数据集名“ Data set name，然后点击“ Create data set ”按钮，退出“ Data”窗口，返回工具箱 界面，这时会自动画出数据集的曲线图；(3) 点击“ Fitting ”按钮，弹出“ Fitting ” 窗口；(4) 点击“ Newfit ”按钮，可修改拟合项目名称“ Fit name ，通过“ Data set 下拉菜单选择数据集，然后通过下拉菜单“ Type of fit ”选择拟合曲线的类型， 工具箱提供的拟合类型有：* Custom Equations :用户自定义的函数类型* Expon

3、ential :指数逼近，有 2 种类型，a*exp(b*x)、a*exp(b*x) + c*exp(d*x)* Fourier:傅立叶逼近，有7种类型，基础型是 a0 + a1*cos(x*w) + b1*sin(x*w)* Gaussian :高斯逼近，有8种类型，基础型是 a1*exp(-(x-b1)/c1)A2)* Interpolant :插值逼近，有 4 种类型，linear、nearest neighbor、cubic spline、 shape-preserv ing* Polynomial :多形式逼近，有 9 种类型，linear 、quadratic 、cubic 、4-

4、9th degree * Power:幕逼近，有 2 种类型，a*xAb、a*xAb + c* Rational :有理数逼近，分子、分母共有的类型是 linear 、quadratic 、cubic 、4-5th degree ;此外，分子还包括 constant型* Smoothing Spline :平滑逼近(翻译的不大恰当，不好意思)* Sum of Sin Functions :正弦曲线逼近，有 8种类型，基础型是 a1*sin(b1*x + c1)* Weibull :只有一种，a*b*xA(b-1)*exp(-a*xAb)选择好所需的拟合曲线类型及其子类型，并进行相关设置：如果是

5、非自定义的类型，根据实际需要点击“Fit optio ns ”按钮，设置 拟合算法、修改待估计参数的上下限等参数；如果选CustomEquations，点击“ NeW按钮，弹出自定义函数等式窗口， 有“ Li near Equatio ns线性等式”和“ Ge neral Equatio ns 构造等式”两种标签。在本例中选 CustomEquations，点击“ New 按钮，选择“ General Equations ” 标签，输入函数类型y=a*x*x + b*x，设置参数a、b的上下限，然后点击 0K(5) 类型设置完成后，点击“ Apply”按钮，就可以在Results框中得到拟合

6、结果。下面是一个实例：建立M文件，COP下面内容至M文件中：(这是真实实验数据，比较长，直接COPY就可以，copy至“ cftool”)clcclear allx=010 20 30 40 50 60 70 80 90 100110 120 130 140 150 160 170180 190 200 210220 230 240 250 260270 280 290300 310 320 330 340350360 370 380 390400 410 420 430 440450 460 470480 490 500 510 520530540 550 560 570580 590 60

7、0 610 620630 640 650660 670 680 690 700710720 730 740 750760 770 780 790 800810 820 830840 850 860 870 880890900 910 920 930 940 950 960 970 980 990 1000101010201030104010501060107010801090110011101120113011401150116011701180119012001210122012301240125012601270128012901300131013201330134013501360137

8、013801390140014101420143014401450146014701480149015001510152015301540155015601570158015901600161016201630164016501660167016801690170017101720173017401750176017701780179018001810182018301840185018601870188018901900191019201930194019501960197019801990200020102020203020402050206020702080209021002110212

9、021302140215021602170218021902200221022202230224022502260227022802290230023102320233023402350236023702380239024002410242024302440245024602470248024902500251025202530254025502560257025802590260026102620263026402650266026702680269027002710272027302740275027602770278027902800281028202830284028502860287

10、028802890290029102920293029402950296029702980299030003010302030303040305030603070308030903100311031203130314031503160317031803190320032103220323032403250326032703280329033003310332033303340335033603370338033903400341034203430344034503460347034803490350035103520353035403550356035703580359036003610362

11、036303640365036603670368036903700371037203730374037503760377037803790380038103820383038403850386038703880389039003910392039303940395039603970398039904000401040204030404040504060407040804090410041104120413041404150416041704180419042004210422042304240425042604270428042904300431043204330434043504360437

12、043804390440044104420443044404450446044704480449045004510452045304540455045604570458045904600461046204630464046504660467046804690470047104720473047404750476047704780479048004810482048304840485048604870488048904900491049204930494049504960497049804990500050105020503050405050506050705080509051005110512

13、051305140515051605170518051905200521052205230524052505260527052805290530053105320533053405350536053705380539054005410542054305440545054605470548054905500551055205530554055505560557055805590560056105620563056405650566056705680569057005710572057305740575057605770578057905800581058205830584058505860587

14、058805890590059105920593059405950596059705980599060006010602060306040605060606070608060906100611061206130614061506160617061806190620062106220623062406250626062706280629063006310632063306340635063606370638063906400641064206430644064506460647064806490650065106520653065406550656065706580659066006610662

15、066306640665066606670668066906700671067206730674067506760677067806790680068106820683068406850686068706880689069006910692069306940695069606970698069907000701070207030704070507060707070807090710071107120713071407150716071707180719072007210722072307240725072607270728072907300731073207330734073507360737

16、07380739074007410742074307440 7450 7460 7470 7480 7490 7500 7510 7520753075407550756075707580759076007610762076307640765076607670768076907700771077207730774077507760777077807790780078107820783078407850786078707880789079007910792079307940795079607970798079908000801080208030804080508060807080808090810

17、0811081208130814081508160817081808190820082108220823082408250826082708280829083008310832083308340;y=3.934 3.893 3.878 3.873 3.862 3.857 3.852 3.847 3.8363.8313.8313.8263.8213.8163.8163.8113.8113.8053.8053.8 3.8 3.7953.7953.7953.793.7953.793.793.7853.793.7853.7853.7853.783.78 3.78 3.783.7743.7743.774

18、3.7743.7743.7743.7693.7693.7693.7693.7693.7693.7693.7693.7693.7693.7693.7693.7643.7643.7643.7643.7643.7643.7643.7643.7643.7643.7643.7643.7593.7593.7593.7593.7593.7593.7593.7593.7593.7593.7593.7593.7593.7593.7593.7593.7543.7593.7593.7543.7543.7543.7543.7543.7543.7543.7543.7543.7543.7543.7543.7493.754

19、3.7543.7493.7493.7543.7493.7543.7543.7493.7543.7493.7543.7493.7543.7493.7493.7493.7493.7493.7493.7493.7493.7493.7493.7493.7493.7443.7493.7493.7443.7443.7443.7443.7443.7443.7443.7443.7443.7443.7383.7443.7443.7443.7443.7443.7443.7383.7383.7383.7383.7383.7383.7383.7383.7383.7383.7383.7383.7333.7383.733

20、3.7333.7333.7333.7333.7333.7333.7333.7333.7333.7333.7283.7283.7283.7283.7283.7283.7283.7283.7283.7283.7283.7283.7233.7283.7283.7283.7283.7283.7283.7233.7233.7233.7183.7233.7233.7233.7233.7183.7233.7233.7183.7183.7183.7183.7183.7183.7183.7183.7183.7183.7183.7183.7133.7183.7183.7133.7133.7133.7133.713

21、3.7133.7133.7133.7133.7133.7133.7133.7133.7133.7133.7073.7133.7073.7073.7073.7073.7073.7073.7073.7073.7073.7023.7023.7023.7073.7023.7023.7023.7023.7023.7023.7023.7023.6973.7023.6973.6973.6973.6973.6973.6973.6973.6973.6973.6923.6923.6923.6923.6923.6923.6923.6923.6923.6873.6923.6873.6923.6923.6873.687

22、3.6873.6923.6873.6873.6873.6873.6873.6923.6873.6873.6873.6873.6873.6873.6823.6873.6873.6823.6823.6823.6823.6823.6823.6823.6763.6823.6763.6763.6763.6763.6763.6713.6713.6763.6713.6713.6713.6713.6713.6713.6663.6713.6713.6713.6663.6713.6713.6713.6663.6663.6663.6663.6663.6663.6663.6613.6613.6613.6613.661

23、3.6613.6613.6613.6613.6613.6563.6563.6563.6563.6563.6563.6513.6513.6563.6513.6513.6513.6513.6513.6453.6513.6453.6453.6453.6453.6453.6453.6453.6453.6453.643.643.6453.64 3.64 3.64 3.64 3.64 3.643.6353.643.6353.6353.643.6353.6353.6353.6353.6353.6353.6353.6353.6353.633.6353.633.633.633.633.63 3.63 3.63

24、3.63 3.63 3.625 3.633.633.6253.6253.6253.6253.6253.6253.6253.6253.6253.623.623.62 3.62 3.62 3.62 3.615 3.6153.6153.6153.6153.6153.6153.6093.6153.6093.6093.6093.6093.6093.6093.6043.6093.6043.6043.6043.6043.6043.6043.6043.6043.6043.6043.6043.6043.6043.6043.5993.5993.5993.5993.5993.5993.5993.5993.5993.

25、5993.5943.5943.5943.5893.5893.5943.5893.5893.5893.5893.5893.5893.5893.5893.5843.5843.5893.5843.5843.5843.5843.5783.5843.5843.5783.5783.5783.5783.5783.5783.5783.5733.5733.5733.5733.5733.5733.5733.5683.5683.5683.5683.5683.5633.5633.5633.5633.5633.5633.5633.5633.5633.5583.5583.5583.5583.5583.5583.5583.

26、5533.5583.5583.5533.5533.5533.5533.5533.5533.5473.5473.5473.5473.5473.5473.5473.5473.5473.5473.5423.5423.5423.5423.5423.5423.5373.5373.5373.5373.5373.5373.5373.5373.5323.5323.5323.5323.5273.5273.5273.5273.5273.5273.5273.5273.5273.5223.5223.5223.5223.5223.5223.5223.5223.5223.5163.5163.5163.5163.5163.

27、5163.5113.5113.5063.5063.5063.5063.5063.5063.5063.5013.5013.5013.5013.4963.4963.4963.4963.4963.4963.4913.4913.4913.4913.4913.4913.4853.4853.4853.4853.483.48 3.48 3.48 3.48 3.48 3.475 3.475 3.475 3.4753.475 3.47 3.47 3.47 3.47 3.47 3.465 3.465 3.4653.4653.4653.4653.4653.463.463.463.46 3.4553.4553.455

28、3.4553.4493.4493.4493.4493.4443.4443.4443.4443.4393.4393.4393.4393.4393.4393.4343.4343.4343.4343.4293.4293.4293.4243.4243.4243.4243.4243.4183.4183.4183.4183.4183.4133.4133.4083.4083.4083.4083.4083.4033.4033.3983.3983.3983.3933.3933.3933.3933.3873.3873.3873.3823.382 3.382 3.382 3.382 3.377 3.377 3.377 3.377 3.3723.3723.3723.3673.3673.3623.3623.3623.3623.3623.3563.3563.3563.3513.3513.3513.3463.3463.3413.3413.3413