get the correct data of intersection in plot

2016 8 5
2 个回答
回答已采纳
更新时间：2016 8 15
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Hi, I'm working on a project in which i want to know the time on which the accuracy lines hit 95% for the first time. I've already looked in some related topics but didn't find any that could help me on it.
Although the figure below contains two sets of lines only the accuracy ones are of importance.
below a simplified representation of the code for this graph.
frequencies = [7.5 15 30 60 120 240];
nfrequencies = numel(frequencies);
duration = 0.2:0.2:8.5;
for a=1:nfrequencies
accuracy(:,a)=(a+2)*(a+2.5)*duration+10;
ltext{a}=[num2str(frequencies(a)), 'Hz'];
end
plot(duration,accuracy)
axis([0.2 8.5 0 102])
legend(ltext,'Location','southeast');

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Jacco vD
Jacco vD 2016-8-15

0 个投票

none of those seem to work this case.
So I fixed it simply like this. It gives me the first time that the accuracy of a given frequency is 95%, which is what in need;)
duration = 0.2:0.2:8
nfrequencies = 6
threshold = accuracy*100>=95;
X = zeros(nfrequencies,1)
for l=1:nfrequencies
fthreshold = find(threshold(:,l));
if fthreshold >= 1
Y = duration(fthreshold(1));
else
Y = max(duration);
end
X(:,l)= Y;
end

更多回答（1 个）

Thorsten
Thorsten 2016-8-5

0 个投票

You can compute the first intersection of each curve with a horizontal line of height 95. There are various ways to compute intersections, as described in http://blogs.mathworks.com/pick/2011/09/09/detect-curve-intersections-quickly-and-easily/?s_tid=srchtitle

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