matlab數(shù)據(jù)擬合,有圖有例子,一看就會(huì)

1、Matlab CFTool 使用簡(jiǎn)介:單一變量的曲線逼近Matlab有一個(gè)功能強(qiáng)大的曲線擬合工具箱 cftool，使用方便，能實(shí)現(xiàn)多種類型的線性、非線性曲線擬合。下面結(jié)合我使用的Matlab R2007b來(lái)簡(jiǎn)單介紹如何使用這個(gè)工具箱。假設(shè)我們要擬合的函數(shù)形式是 y=A*x*x + B*x, 且A>0,B>0。1、在命令行輸入數(shù)據(jù)： x=你的X軸數(shù)據(jù);y=你的丫軸數(shù)據(jù);cftool可以將上面三個(gè)行建立一個(gè)M文件，以便后面進(jìn)行數(shù)據(jù)擬合時(shí)可以直接使用，點(diǎn) 擊運(yùn)行即可進(jìn)入曲線擬合工具箱界面“ Curve Fitti ng tool ”(1) 點(diǎn)擊“ Data”按鈕，彈出“ Data”窗口；

2、(2) 利用X data和丫 data的下拉菜單讀入數(shù)據(jù)x,y，可修改數(shù)據(jù)集名“ Data set name，然后點(diǎn)擊“ Create data set ”按鈕，退出“ Data”窗口，返回工具箱 界面，這時(shí)會(huì)自動(dòng)畫(huà)出數(shù)據(jù)集的曲線圖；(3) 點(diǎn)擊“ Fitting ”按鈕，彈出“ Fitting ” 窗口；(4) 點(diǎn)擊“ Newfit ”按鈕，可修改擬合項(xiàng)目名稱“ Fit name ，通過(guò)“ Data set 下拉菜單選擇數(shù)據(jù)集，然后通過(guò)下拉菜單“ Type of fit ”選擇擬合曲線的類型， 工具箱提供的擬合類型有：* Custom Equations :用戶自定義的函數(shù)類型* Expon

3、ential :指數(shù)逼近，有 2 種類型，a*exp(b*x)、a*exp(b*x) + c*exp(d*x)* Fourier:傅立葉逼近，有7種類型，基礎(chǔ)型是 a0 + a1*cos(x*w) + b1*sin(x*w)* Gaussian :高斯逼近，有8種類型，基礎(chǔ)型是 a1*exp(-(x-b1)/c1)A2)* Interpolant :插值逼近，有 4 種類型，linear、nearest neighbor、cubic spline、 shape-preserv ing* Polynomial :多形式逼近，有 9 種類型，linear 、quadratic 、cubic 、4-

4、9th degree * Power:幕逼近，有 2 種類型，a*xAb、a*xAb + c* Rational :有理數(shù)逼近，分子、分母共有的類型是 linear 、quadratic 、cubic 、4-5th degree ;此外，分子還包括 constant型* Smoothing Spline :平滑逼近(翻譯的不大恰當(dāng)，不好意思)* Sum of Sin Functions :正弦曲線逼近，有 8種類型，基礎(chǔ)型是 a1*sin(b1*x + c1)* Weibull :只有一種，a*b*xA(b-1)*exp(-a*xAb)選擇好所需的擬合曲線類型及其子類型，并進(jìn)行相關(guān)設(shè)置：如果是

5、非自定義的類型，根據(jù)實(shí)際需要點(diǎn)擊“Fit optio ns ”按鈕，設(shè)置 擬合算法、修改待估計(jì)參數(shù)的上下限等參數(shù)；如果選CustomEquations，點(diǎn)擊“ NeW按鈕，彈出自定義函數(shù)等式窗口， 有“ Li near Equatio ns線性等式”和“ Ge neral Equatio ns 構(gòu)造等式”兩種標(biāo)簽。在本例中選 CustomEquations，點(diǎn)擊“ New 按鈕，選擇“ General Equations ” 標(biāo)簽，輸入函數(shù)類型y=a*x*x + b*x，設(shè)置參數(shù)a、b的上下限，然后點(diǎn)擊 0K(5) 類型設(shè)置完成后，點(diǎn)擊“ Apply”按鈕，就可以在Results框中得到擬合

6、結(jié)果。下面是一個(gè)實(shí)例：建立M文件，COP下面內(nèi)容至M文件中：(這是真實(shí)實(shí)驗(yàn)數(shù)據(jù)，比較長(zhǎng)，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