Help with plotting two lines.

So I was given a set of x and y coordinates. We were asked to plot the set with a non-connecting points. Then to create a function that generates the best fit line for the list and plot it on the same chart which I did. But it ended up with a bunch of vertical lines connecting the data points and the best fit line together...(

(I've attached a picture)). How do I remove this? Here is my code if you need it for reference:

function cubicfit(x,y)
xp=x;
yp=y;
plot(xp,yp,'.')
xlabel('X data')
ylabel('Y data')
hold on

%%%%%%%%%%%%%%%%%%%%%%%%%%%%
A=zeros(41,4);
for i=1:length(x)
      A(i,1)=[((x(i))^3)];
end
for i=1:length(x)
      A(i,2)=[((x(i))^2)];
end
for i=1:length(x)
      A(i,3)=[((x(i))^1)];    
end
for i=1:length(x)
      A(i,4)=[((x(i))^0)];
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
c=(((A')*A)^-1)*((A')*y)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for i=1:length(x)
y(i)=((c(1)*(x(i)))^3)+((c(2)*(x(i)))^2)+((c(3)*(x(i))))+(c(4));
plot(x,y,'-')

end

Answer 1

[Walter Roberson]

In the sequence

for i=1:length(x)
y(i)=((c(1)*(x(i)))^3)+((c(2)*(x(i)))^2)+((c(3)*(x(i))))+(c(4));
plot(x,y,'-')

end

you are defining one new y value at a time, but you are plotting all the y values each time.

You need to postpone the plot to after the loop.

[Matthew Lozancich]

Yuppp that was the problem. This literally gets me every time. Once again, thank you!