Matlab Minimos Cuadrados

Minimos cuadrados grado 1

clc
clear all
close all

%M?NIMOS CUADRADOS

xi=[0.05 0.11 0.15 0.31 0.46 0.52 0.7 0.74 0.82 0.98 1.17];
yi=[0.956 0.89 0.832 0.717 0.571 0.239 0.378 0.37 0.3060.242 0.104];
n=11;
l1=0;l2=0;l3=0;l4=0;
l1old=l1;l2old=l2;l3old=l3;l4old=l4;

for i=1:n
z1=xi(i);
l1=l1old+z1;
l1old=l1;

z2=yi(i);
l2=l2old+z2;
l2old=l2;z3=(xi(i))^2;
l3=l3old+z3;
l3old=l3;

z4=xi(i)*yi(i);
l4=l4old+z4;
l4old=l4;
end

syms a b

U=[l1,l2,l3,l4,n,a,b];

f1=l4-a*l3-b*l1;
f1s=subs(f1,U,[l1,l2,l3,l4,n,a,b]);f2=l2-a*l1-b*n;
f2s=subs(f2,U,[l1,l2,l3,l4,n,a,b]);

X=solve(f1s,f2s);
a=double(X.a);
b=double(X.b);

syms x
y=a*x+b;
y=simplify(y)
pretty(y);

dom=10:0.1:100;
fun=inline('y');
plot(dom,fun(dom),'r')
ylabel('yi');
xlabel('xi');










Minimos cuadrados grado 2

clc
clear all
close all

%minimos cuadrados grado 2
xn=[0.05 0.11 0.15 0.31 0.46 0.52 0.7 0.74 0.82 0.981.17];
yn=[0.956 0.89 0.832 0.717 0.571 0.239 0.378 0.37 0.306 0.242 0.104];
n=length(xn);
l1=0;l2=0;l3=0;l4=0;l5=0;l6=0;l7=0;
l1old=l1;l2old=l2;l3old=l3;l4old=l4;l5old=l5;l6old=l6;l7old=l7;for i=1:n
z1=xn(i);
l1=l1old+z1;
l1old=l1;

z2=yn(i);
l2=l2old+z2;
l2old=l2;

z3=(xn(i))^2;
l3=l3old+z3;
l3old=l3;

z4=xn(i)*yn(i);l4=l4old+z4;
l4old=l4;

z5=(xn(i))^3;
l5=l5old+z5;
l5old=l5;

z6=(xn(i))^4;
l6=l6old+z6;
l6old=l6;

z7=((xn(i))^2)*yn(i);
l7=l7old+z7;
l7old=l7;
endsyms a b c

U=[l1,l2,l3,l4,l5,l6,l7,n,a,b,c]

f1=l2-a*n-b*l1-c*l3;
f1s=subs(f1,U,[l1,l2,l3,l4,l5,l6,l7,n,a,b,c]);

f2=l4-a*l1-b*l3-c*l5;
f2s=subs(f2,U,[l1,l2,l3,l4,l5,l6,l7,n,a,b,c]);f3=l7-a*l3-b*l5-c*l6;
f3s=subs(f3,U,[l1,l2,l3,l4,l5,l6,l7,n,a,b,c]);

X=solve(f1s,f2s,f3s)
a=double(X.a);
b=double(X.b);
c=double(X.c);

syms x

p=a+b*x+c*(x^2);
p=simplify(p)
pretty(p)...