clc;close; clear;
% R1=10;
% R2=12;
% R3=13;
% R4=10;
% R5=12;
% V1=1;
% V2=3;
% A=[(R1+R2), -R2, 0;...
%     -R2, (R2+R3+R4), -R4;...
%     0, R4,   (R4+R5)];
% B=[V1;...
%     0;...
%     V2];
% A = [2, -1, 0; -1, 3, -1; 0, -1, 2];
% B = [5; 0; -5];
% X=A\B
% X=inv(A)*B
% error=sum(A*X-B)
 x = [0.0, 1.0, 2.0, 3.0, 4.0, 5.0 6.0]';
 y = [0.0, 20.0, 60.0, 68.0, 77.0, 110.0, 22]';
 x1=0:0.01:6
 for ii=1:8
 coef = polyfit(x,y,ii);
 y1= polyval(coef,x1);
 subplot(4,2,ii)
 plot(x,y,x1,y1)
 end

% x=sqrt(2);
% y=0;
% a=1
% b=1
% c=0;
% a*x+b*y+c
% 
% a1=a/sqrt(a^2+b^2);
% b1=b/sqrt(a^2+b^2);
% c1=c/sqrt(a^2+b^2);
% (a1*x+b1*y+c1)^2
%[x,y]=meshgrid(0:8,0:8)
%V=sin(x+y);
%[x1,y1]=meshgrid(0:0.1:8,0:0.2:8)
%S=interp2(x,y,V,x1,y1)
%surf(x1,y1,S)