MATLAB拟合曲线

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今天想帮朋友做一个简单的数据拟合，然后画图，结果发现网上都没有现成的模板，只能自己摸索了，最后搜到了一个简单的方法，将多条曲线放到一个图上。
以下是数据：

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X1 =
         0    0.8800
    4.0000    1.0400
    8.0000    1.0200
   12.0000    1.1000
x1 =
     0     4     8    12
y1 =
    0.8800    1.0400    1.0200    1.1000
X2 =
         0    2.1600
    4.0000    3.0500
    8.0000    3.2400
   12.0000    3.9500
x2 =
     0     4     8    12
y2 =
    2.1600    3.0500    3.2400    3.9500
X3 =
         0    4.2900
    4.0000    3.2300
    8.0000    2.8600
   12.0000    3.3200
   16.0000    4.7900
x3 =
     0     4     8    12    16
y3 =
    4.2900    3.2300    2.8600    3.3200    4.7900

注意画图的x与y都必须是行向量
首先做拟合，这个很简单，命令行中输入cftool就可以了，曲线类型选择smoothingspline平滑曲线，选择x1，y1，就可以得到第一条拟合曲线了，但是怎么样将多条拟合曲线画在一张图上呢，首先在cftool中选择fit->new fit，然后依次得到第二条与第三条拟合曲线，然后在file->generate code中得到画图的代码，如下：

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function [fitresult, gof] = createFits1(x1, y1, x2, y2, x3, y3)
%CREATEFITS1(X1,Y1,X2,Y2,X3,Y3)
%  Create fits.
%
%  Data for 'untitled fit 1' fit:
%      X Input : x1
%      Y Output: y1
%  Data for 'untitled fit 3' fit:
%      X Input : x2
%      Y Output: y2
%  Data for 'untitled fit 4' fit:
%      X Input : x3
%      Y Output: y3
%  Output:
%      fitresult : a cell-array of fit objects representing the fits.
%      gof : structure array with goodness-of fit info.
%
%  See also FIT, CFIT, SFIT.

%  Auto-generated by MATLAB on 12-Oct-2016 20:52:56

%% Initialization.

% Initialize arrays to store fits and goodness-of-fit.
fitresult = cell( 3, 1 );
gof = struct( 'sse', cell( 3, 1 ), ...
    'rsquare', [], 'dfe', [], 'adjrsquare', [], 'rmse', [] );

%% Fit: 'untitled fit 1'.
[xData, yData] = prepareCurveData( x1, y1 );

% Set up fittype and options.
ft = fittype( 'smoothingspline' );

% Fit model to data.
[fitresult{1}, gof(1)] = fit( xData, yData, ft );

% Plot fit with data.
figure( 'Name', 'untitled fit 1' );
h = plot( fitresult{1}, xData, yData );
legend( h, 'y1 vs. x1', 'untitled fit 1', 'Location', 'NorthEast' );
% Label axes
xlabel x1
ylabel y1
grid on

%% Fit: 'untitled fit 3'.
[xData, yData] = prepareCurveData( x2, y2 );

% Set up fittype and options.
ft = fittype( 'smoothingspline' );

% Fit model to data.
[fitresult{2}, gof(2)] = fit( xData, yData, ft );

% Plot fit with data.
figure( 'Name', 'untitled fit 3' );
h = plot( fitresult{2}, xData, yData );
legend( h, 'y2 vs. x2', 'untitled fit 3', 'Location', 'NorthEast' );
% Label axes
xlabel x2
ylabel y2
grid on

%% Fit: 'untitled fit 4'.
[xData, yData] = prepareCurveData( x3, y3 );

% Set up fittype and options.
ft = fittype( 'smoothingspline' );

% Fit model to data.
[fitresult{3}, gof(3)] = fit( xData, yData, ft );

% Plot fit with data.
figure( 'Name', 'untitled fit 4' );
h = plot( fitresult{3}, xData, yData );
legend( h, 'y3 vs. x3', 'untitled fit 4', 'Location', 'NorthEast' );
% Label axes
xlabel x3
ylabel y3
grid on

根据这一段代码其实就可以发现我们其实根本不需要打开cftool，直接写代码就可以得到拟合曲线，通过hold on就可以很轻易的将不同的曲线画在同一张图上了，具体代码如下：

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ft = fittype( 'smoothingspline' );
[fit1, gof] = fit( x1', y1', ft );
[fit2, gof] = fit( x2', y2', ft );
[fit3, gof] = fit( x3', y3', ft );
h=plot( fit1, x1, y1 );
set(h,'Color','g')
hold on
h1=plot( fit2, x2, y2 );
set(h1,'Color','r')
hold on
h2=plot( fit3, x3, y3 );
set(h2,'Color','b')

通过set更改曲线的颜色，注意Color要大写，小写只会改数据点的颜色
其他的设置像图例坐标轴标题什么的百度一下就好