Finding a parabolic function having two known points and curve shape

Hi,

I want to build a vector y that follows a parabolic function having two sets of points: (1,0.03) and (n,0), being n a variable that is defined earlier in my code. This means that the vector indexes go from 1 to n, being y(1) = 0.03 and y(n) = 0.

The curve must look like this (pardon my sloppy Paint skills):

I thought of creating a for loop, but don't know what to put inside it. Something like:

for i = 1:n
     y(i) = %(insert polynomial function which I can't figure out here)
end

Any thoughts?

Thanks!

Answer 1

[Matt J]

p=polyfit([2-n, 1,n], [0, .03,0] ,2);

y=polyval(p,1:n)

[Rafael Pereira de Resende Freitas]

Thanks for your reply! That works. Could you however please explain how you got to this? I may need to adapt it in a few other parts of my code.

[Matt J]

We used polyfit to get the coefficients, p, of the parabola from the known points that it passes through.

Then we used polyval to evaluate the parabola on 1:n.

[Rafael Pereira de Resende Freitas]

Thank you very much.