scatter random points around polynom

I am trying to create random points around a defined polynomial.

The polynomial is created with defined points.

I have the polynom but I cannot creat the random points. Can someone please help me?

x_poly = [700 750 730 630 700 745 830 765 700]; 
y_poly = [0 266 570 780 1150 1300 1580 1880 2400];
%Create Polynom based on used point coordinates
t = (1:length(x_poly))';
Px = polyfit(t,x_poly,5);
Py = polyfit(t,y_poly,5);
ti = linspace(min(t),max(t));
plot(x_poly,y_poly,'o',polyval(Px,ti),polyval(Py,ti),'-')

Answer 1

[Stefano Ferrari]

Just managed to do it:

x_poly = [700 750 730 630 700 745 830 765 700]; 
y_poly = [0 266 570 780 1150 1300 1580 1880 2400];

t = (1:length(x_poly));
Px = polyfit(t,x_poly,7);
Py = polyfit(t,y_poly,7);
ti = linspace(min(t),max(t),600);
x=polyval(Px,ti+rand(1,600));
y=polyval(Py,ti+rand(1,600));

scatter(x,y)

Answer 2

[KSSV]

x_poly = [700 750 730 630 700 745 830 765 700]; 
y_poly = [0 266 570 780 1150 1300 1580 1880 2400];
%Create Polynom based on used point coordinates
t = (1:length(x_poly));  %<--- no transpose 
Px = polyfit(t,x_poly,5);
Py = polyfit(t,y_poly,5);
ti = linspace(min(t),max(t));
plot(x_poly,y_poly,'o',polyval(Px,ti),polyval(Py,ti),'-')

[Stefano Ferrari]

That does not change anything

[KSSV]

Your error is solved...that's what I did. What exactly you want ?

[Stefano Ferrari]

I want to scatter points around the polynom (see picture).