Matlab 自定义函数拟合

%RandomAccess J0237_2 reference

%BasketballPass,BQSqare, BlowingBubbles,RaceHorses,

close all;

clear all;

RD = [

1507.09 40.64

755.76 36.89

376.83 33.56

196.96 30.77

1610.73 37.97

631.13 34.63

284.29 31.81

141.13 29.12

1634.23 38.18

749.48 34.79

353.55 31.62

166.08 28.72

1193.66 39.44

587.38 35.73

288.11 32.34

144.13 29.56

];

RD_s(1,1:4,1:2) = RD(1:4,:);

RD_s(2,1:4,1:2) = RD(5:8,:);

RD_s(3,1:4,1:2) = RD(9:12,:);

RD_s(4,1:4,1:2) = RD(13:16,:);

n = 4;

sample_number = 4;

colorset = {{'rx','r-','r--'},{'bo','b-','b--'},{'gd','g-','g--'},{'m+','m-','m--'}};

for seq_id = 1:1:n

x = RD_s(seq_id,:,1); %rate

y = RD_s(seq_id,:,2); %distortion

%method 1

fx = inline('a(1)*(x.^2) + a(2)*sqrt(x) + a(3)','a','x');

a = nlinfit(x,y,fx,[1 1 1]);

x1 = min(x):20:max(x);

y1 = a(1)*(x1.^2) + a(2)*sqrt(x1) + a(3);

%method 2

fx2 = polyfit(x,y,2);

yvalue = polyval(fx2,x);

x2 = x1;

y2 = polyval(fx2,x2);

%y2 = fx(1)*x1.^2 + fx(2)*x1 + fx(3); %polyval(fx,x1);

plot(x,y,colorset{1,seq_id}{1,1},x1,y1,colorset{1,seq_id}{1,2});

hold on

plot(x2,y2,colorset{1,seq_id}{1,3});

grid on;

end

% for seq_id = 1:1:n

% x = RD_s(seq_id,:,1); %rate

% y = RD_s(seq_id,:,2); %distortion

% fx = polyfit(x,y,2);

% yvalue = polyval(fx,x);

% x1 = 0:20:max(x);

% y1 = polyval(fx,x1);

% %y2 = fx(1)*x1.^2 + fx(2)*x1 + fx(3); %polyval(fx,x1);

% plot(x,y,colorset{1,seq_id}{1,1},x1,y1,colorset{1,seq_id}{1,2});

% hold on

% grid on;

% end