How to plot polynomial function correctly?
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From the given cooeficient polynomial functions how to draw an graph in matlab
P(x) = a_0+a_1x+a_2x^2. Whose graph passes through the points (1, 4), (4,73) and (5, 18). Also plot the function using MATLAB command (having proper title, x and y axis notation).
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Steven Lord
2022-8-31
This sounds like a homework assignment. If it is, show us the code you've written to try to solve the problem and ask a specific question about where you're having difficulty and we may be able to provide some guidance.
If you aren't sure where to start because you're not familiar with how to write MATLAB code, I suggest you start with the free MATLAB Onramp tutorial to quickly learn the essentials of MATLAB.
If you aren't sure where to start because you're not familiar with the mathematics you'll need to solve the problem, I recommend asking your professor and/or teaching assistant for help.
采纳的回答
Walter Roberson
2022-8-31
0 个投票
polyfit() and polyval() and plot()
7 个评论
Fozle Rabbi
2022-8-31
Walter Roberson
2022-8-31
Look at the documentation for each of the functions. They have examples.
Fozle Rabbi
2022-8-31
Walter Roberson
2022-8-31
You can ask specific questions. The code takes a very small number of lines, the labels and so on are more than half of the work.
Fozle Rabbi
2022-9-1
Walter Roberson
2022-9-1
You need to choose the x values to plot over.
You will use the given points to figure out what the coefficients are for the polynomial.Then, y will be the polynomial evaluated at your chosen x locations.
syms x [3 1]
syms y [3 1]
vand = [ones(3,1), x, x.^2];
a0123 = simplify(vand \ y, 'steps', 20)
sample_x = sort(randperm(10,3).');
sample_y = randi(100, 3, 1);
[sample_x, sample_y]
A0123 = simplify(subs(a0123, [x; y], [sample_x;sample_y]), 'steps', 20)
X = -1:11;
Y = polyval(double(fliplr(A0123.')), X)
plot(X, Y); hold on
scatter(sample_x, sample_y, 'r*'); hold off
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