确定实验数据，用不同的最小二乘法 ---线性拟和表达式------ 确定系数------- 做出图像 -------------matlab

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于 2018-12-01 11:07:34 发布

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x=[0 10 20 30 40 80 90 95]';
y=[68 67.1 66.4 65.6 64.6 61.8 61 60]';
x1=ones(8,1);
z=[x x1]\y;
a=z(1);
b=z(2);
v=linspace(0,95,100);
plot(x,y,'b-+',v,a*v+b,'k-');
plot(x,y,'LineWidth',3,'Marker','diamond','MarkerEdgeColor','k', ...
 'MarkerFaceColor','y','MarkerSize',2,'Color','r');
title('多项式');

T = [0     10    20    30    40     80     90      95];
s = [68.0  67.1  66.4  65.6  64.6  61.8   61.0   60.0];
q=0;w=0;e=0;r=0;p=0;
for i=1:8,
    q=q+1;
    w=w+T(i);
    e=e+T(i)*T(i);
    r=r+s(i);
    p=p+s(i)*T(i);
end
A=[q w:w e];
B=[r:p];
Z=A\B;
F=Z(2,1).*T+Z(1,1);
L=polyfit(T,s,1);
b=L(2);
a=L(1);
Y=a.*T+b;
hold on ;
plot(T,Y,'r*--')

>> a
a =
   -0.0799
>> b
b =
   67.9593




>> L

L =

   -0.0799   67.9593

>> a

a =

   -0.0799

>> b

b =

   67.9593