help with quadratic function graph

need help making a quadratic growth graph where the maximum of 22.0 is at center with 0.55 on the ends. The x range is from 1 - 15 so need 0.55 at 1 and 0.55 at 15 with 22 at 8. please help

Answer 1

[Ameer Hamza]

Try this

x = [1 8 15];
y = [0.55 22 0.55];

ft = fittype('a*x^2+b*x+c');

fit_quad = fit(x',y',ft);

xv = linspace(x(1), x(end), 100);
yv = fit_quad(xv);

plot(xv,yv);

xlim([x(1) x(end)]);
ylim([0.55 22]);

[random1072]

It did work thank you, only thing I’m getting a warning for is that it says “warning: start point not provided, choosing random start point”

[Ameer Hamza]

This is not an issue. This is just a warning that the function is choosing a random initial point for the optimization algorithm. You can suppress this warning by providing your own starting point

fit_quad = fit(x',y',ft, 'StartPoint', rand(1,3));