clc clear all x=[0.1 0.2 0.4 0.5 1 2] y=[21 11 7 6 5 6] N=length(x) M=[sum(x) sum(1./sqrt(x)); sum(1./sqrt(x)) sum(1./(x.^2))] %for element wise multiplication use . operator B=[sum(y.*x.^(1/2)); sum(y./x)]

L=inv(M)*B

f=L(1)sqrt(x)+ L(2)(1./x) plot(x,y,'*r') hold on plot(x,f,'b-')

x1=[-2 -1 0 1 2]; y1=[15 1 1 3 19]; syms a b x y d g = @(a,b,d,x,y)((y-a-(bx)-(dxx)))^2; g1 = @(a,b,d,x)(a+(bx)+(dx.^2)); h = diff(g,a); h1 = diff(g,b); h2 = diff(g,d); k = subs(h, {x,y}, {x1,y1}); k1 = subs(h1, {x,y}, {x1,y1}); k2 = subs(h2, {x,y}, {x1,y1}); m = sum(k); m1 = sum(k1); m2 = sum(k2); equations = [m==0, m1==0, m2==0] [A c] = equationsToMatrix(equations); X=inv(A)c; a1=X(1) b1=X(2) d1 = X(3); f=g1(a1,b1,d1,x1); plot(x1,y1,x1,f)