How to make plots with symbols(representing data points) and a fitting curve (fit the points with polynomial or other curve equations)

This is the code I have right which gives a smooth curve passing through the data points:

figure

x1 = [0,0.0521,0.1042, 0.1563, 0.2083, 0.2604, 0.3125, 0.3646, 0.4167];

x1q = linspace(x1(1),x1(end),100);

y1 = [2.4015, 2.9473, 4.5847, 5.7855, 7.4229, 9.6061, 12.2259, 13.2083, 13.6450];

y1q = interp1(x1,y1,x1q,'pchip');

x2 = [0, 0.0510, 0.1020, 0.1531, 0.2041, 0.2551];

x2q = linspace(x2(1),x2(end),100);

y2 = [1.6836, 2.3150, 3.2620, 3.9986, 4.9456, 6.8397];

y2q = interp1(x2,y2,x2q,'pchip');

plot(x1q,y1q,'r',x2q,y2q,'b')

hold on

plot(x1,y1,'rx',x2,y2,'bo')

Answer 1

[Star Strider]

Try this:

b1 = polyfit(x1, y1, 1);                                        % Linear Function
y1p = polyval(b1, x1q);

b2 = polyfit(x2, y2, 3);                                        % 3-Degree Polynomial
y2p = polyval(b2, x2q);

figure
plot(x1, y1, '+r',    x1q, y1p, '-r')
hold on
plot(x2, y2, 'ob',    x2q, y2p, '-b')
hold off
grid

See the documentation for polyfit (link) for details.

Experiment to get the result you want.