Plot parabola with start, end and vertex points
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Hi,
So I have three points and I would like matlab to plot them as a parabola. The points represent the path of a balls projectile motion and I know the start (0,0), end (2.062, 0) and high point (1.031, 0,73) of the parabola.
What I would like most would be to plot these points as a parabola and also calculate the equation for the parabola.
Thanks in advance :)
Freyja
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Accepted Answer
Roger Stafford
on 11 Nov 2013
Another way to get the parabola is to write:
y = 0.73-a*(x-1.031)^2
which is the form it must have to peak at (1.031,0,73) and then set x and y to zero to force the parabola to contain (0,0) and solve for a. The solution is obvious. Then do a plot.
More Answers (1)
Matt J
on 11 Nov 2013
Edited: Matt J
on 11 Nov 2013
You can use POLYFIT to fit a parabola to the points. Then you can use POLYVAL to sample and plot it.
4 Comments
Matt J
on 11 Nov 2013
But this gave me a triangle....not a parabola....
It only looks like a triangle, because you didn't plot at enough points
xu=linspace(0,2.06,1000);
plot(xu, polyval(p, xu));
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