How can I find intersection points without mouse?

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Hossein Alishahi
Hossein Alishahi 2021-3-7
评论： Walter Roberson 2025-1-2
Hi,
I hope you are keeping safe.
Couls you please help me regarding my matlab code, It is urgent and I would appreciate if you help me. I want to find intersections in this plot without mouse(Using code).
%% Input Parameters
clear all
clc
alpha1=input('Enter positive "alpha1"?');
alpha2=input('Enter positive "alpha2"?');
beta1=input('Enter positive "beta1"?');
beta2=input('Enter positive "beta2"?');
lambda=input('Enter positive "lambda"?');
eta1=input('Enter positive "eta1"?');
eta2=input('Enter positive "eta2"?');
P=input('Enter positive "P"?');
%% Feasible Area
x = -1:P;m = 0; c = eta2; y = m * x + c;
plot(x, y, 'black')
y = -1:P; m = 0; c = eta1; y = m * x + c;
plot(y, x, 'black')
eta1=min (eta1,P); eta2=min (eta2,P);
if eta1+eta2<P
X=[0 0 eta1 eta1]; Y=[0 eta2 eta2 0];
fill(X,Y,[0.85 0.85 0.85]);
else
X=[0 0 P-eta2 eta1 eta1]; Y=[0 eta2 eta2 P-eta1 0];
fill(X,Y,[0.85 0.85 0.85]); axis([-1 P -1 P])
end
X=[0 0]; Y=[0 P];
line(X,Y,'Color','black')
hold on
line(Y,X,'Color','black')
g = @(x,y) x+y-P;
gp =fimplicit(g,[0 P 0 P], 'black')
f = @(x,y) log((1+alpha1*x./(1+alpha2*y))) -lambda*log((1+beta1*x./(1+beta2*y)));
fp =fimplicit(f,[-1 P -1 P], '-')
hold on
grid on
For alpha1=1 , alpha2=0.2, beta1=1,beta2=2, lambda=2, eta1=3,eta2=4, P=2
Many Thanks in advance
  3 个评论
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Hossein Alishahi
Hossein Alishahi 2021-3-8
Firstly , If you read my request carefully, I have not claimed that my question is more unrgent than others. Secondly, you can run ginput function and then select your desired coordinate from lines by using mouse.
Thanks,
Jan
Jan 2021-3-8
Some members of this forum react allergic to the term "urgent", see e.g. https://www.mathworks.com/matlabcentral/answers/29922-why-your-question-is-not-urgent-or-an-emergency .
You are drawing some objects. I cannot guess between which of these obejcts you want to locate the interection. The more the readers have to guess, the longer takes it to answer.

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回答（1 个）

Gautam
Gautam 2025-1-2
编辑：Gautam 2025-1-2
Hello Hossein,
If you want to find the point of intersection of any tow lines programmatically, you can do so following the steps below:
  1. Create handles to the line objects for which you want to find the intersection point, like:
line1 = line(X,Y,'Color','black');
line2 = line(Y,X,'Color','black');
2. Use the “XData” and “YData” properties of the line objects to find the point of intersection:
interX = line1.XData(line1.XData == line2.XData);>>interY = line1.YData(line1.YData == line2.YData);
3. You can show the point of intersection on the plot using
plot(interX, interY, 'rO', 'MarkerSize',6, 'MarkerFaceColor','red')
Plotting the point of intersection of the lines produces the following graph
You can use the same steps to find the point of intersection of any two lines in your code
  1 个评论
Walter Roberson
Walter Roberson 2025-1-2
Ran in:
Comparing the XData and YData properties of two lines will generally not work.
X = [0 3];
Y = [1 2];
line1 = line(X,Y,'Color','black');
line2 = line(Y,X,'Color','black');
●
interX = line1.XData(line1.XData == line2.XData);
interY = line1.YData(line1.YData == line2.YData);
plot(interX, interY, 'rO', 'MarkerSize',6, 'MarkerFaceColor','red')
There is no-place that the XData from the one line happens to be exactly the XData from the other line.
The XData property does not interpolate. The result is not the same as
cla
X = 0:.1:3;
Y = linspace(1,2,numel(X));
line1 = line(X,Y,'Color','black');
line2 = line(Y,X,'Color','black');
interX = line1.XData(line1.XData == line2.XData);
interY = line1.YData(line1.YData == line2.YData);
plot(interX, interY, 'rO', 'MarkerSize',6, 'MarkerFaceColor','red')

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