Hello everyone. I am tasked to create a function that will receive two vectors and apply polynomial fitting based on the least squares method. In class we were given this code to build off of. Unfortunately, I'm having difficulty understanding it.
function b=inclasslab5(x,y,m)
if length(x)~=length(y)
error(' ')
elseif m+1>length(x)
error(' ')
else
end
a=zeros(m+1);
d=zeros(m+1,1);
for j1=1:m+1
for j2=1:m+1
a(j1,j2)=sum(x.n*(2*m+2-j1*j2))
end
end
for j1=1:m+1
d(j1)=sum(x.n*(m+1-j1)*y)
end
c=rref([a,d])
b=c(:,m+2)
When I apply the given vectors, I get the following error message: "Struct contents reference from a non-struct array object. Error in inclasslab5 (line 16): a(j1,j2)=sum(x.n*(2*m+2-j1*j2))". I'm almost certain it has to do with the value n.
Ultimately, this value b needs to be applied to my script file which plots the data.
clc
x=[1.5 -2.3 5 -4 7 -1 3 0.8 -2 4.2 1.3 1.4 0 0.9 1.7 -4]
y=[-0.1 1.2 3.4 -4 3 -1.5 3.3 5.2 0.7 7 -3 9 4 8 2 7]
xmin=min(x)
xmax=max(x)
x1=linspace(xmin,xmax)
y1=b(1)*x1+b(2)
y2=b(1)*x1.^2+b(2)*x1+b(3)
y3=b(1)*x1.^3+b(2)*x1.^2+b(3)*x1+b(4)
plot(x,y,'o',x1, y1,'b',x1,y2,'r',x1,y3,'g')
