lab 5 / my_polyfit

function my_polyfit (fn,N)
filename=fn;
if (exist(filename)~=2)
disp('file does not exist')
return
end% if
M=read_matrix(fn);
x=M(:,1);
y=M(:,N+1);
plot(x,y,'ro')

a=polyfit(x,y,5);
a1=polyfit(x,y,1);
t=x(1):0.1:x(end);
f=polyval(a,t);
f1=polyval(a1,t);


figure;
grid on;
plot(x,y,'colour','r','marker','o','Markersize',10)
plot(t,f,'b-',t,f1,'g-.')
Grid on;
title('polynormial regress');