Hello, how do I display the equation for a polyfit line on this plot?
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if true
% code
end
p = polyfit(x,y,1);
d = polyval(p,x);
plot(x,d,'k--')
where x and y are columns of 9, averaged from 3 original sets of 9 data point columns each.
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Steven Lord
2021년 6월 2일
One tweak is that you can include + in the format specifier itself to avoid "+ -<number>" while displaying the sign. Look at the linear term in txt1 and txt2.
a = 2;
b = -pi;
c = exp(1);
txt1 = sprintf('y = %.4f*x^2 +%.4f*x +%.4f', a, b, c)
txt2 = sprintf('y = %.4f*x^2 %+.4f*x %+.4f', a, b, c)
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Image Analyst
2018년 5월 17일
Use text() to display the equation on the graph:
grid on;
% Place equation in upper left of graph.
xl = xlim;
yl = ylim;
xt = 0.05 * (xl(2)-xl(1)) + xl(1)
yt = 0.90 * (yl(2)-yl(1)) + yl(1)
caption = sprintf('y = %f * x + %f', p(1), p(2));
text(xt, yt, caption, 'FontSize', 16, 'Color', 'r', 'FontWeight', 'bold');
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the cyclist
2018년 5월 17일
편집: the cyclist
2018년 5월 17일
Here is an example of how you can do this.
There are more efficient ways (e.g. using polyval on both the min and max at the same time), but I thought this might be clearer.
rng default
N = 10; x = randn(N,1); y = x + 0.3*randn(N,1);
p = polyfit(x,y,1);
x_min = min(x); x_max = max(x);
d_min = polyval(p,x_min); d_max = polyval(p,x_max);
figure hold on scatter(x,y) plot([x_min x_max],[d_min d_max],'k--')
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the cyclist
2018년 5월 17일
Ah, I misunderstood the question. I thought you wanted to graph the equation, and it was not working.
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