Finding a parabolic function having two known points and curve shape

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Rafael Pereira de Resende Freitas
评论： Rafael Pereira de Resende Freitas 2018-10-18
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!

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Matt J
Matt J 2018-10-17
编辑：Matt J 2018-10-17
p=polyfit([2-n, 1,n], [0, .03,0] ,2);
y=polyval(p,1:n)
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Matt J
Matt J 2018-10-17
编辑：Matt J 2018-10-17
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.

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