How to find intersection between lines

Question

Hossein Alishahi 2021-3-6

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/764726-how-to-find-intersection-between-lines

评论： darova 2021-3-7

I have below code

%% Input Values

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==0 && eta2==0;

X=[0 0 P]; Y=[0 P 0];

fill(X,Y,[0.85 0.85 0.85]); axis([-1 P -1 P])

end

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;

y1=fimplicit(g,[0 P 0 P])

f = @(x,y) log((1+alpha1*x./(1+alpha2*y))) -lambda*log((1+beta1*x./(1+beta2*y)));

y2=fimplicit(f,[-1 P -1 P], '-')

hold on

grid on

Where I consider alpha1=1, alpha2=0.2, beta1=1; beta2=2, lambda=2, eta1=2, eta2=3, P=1

I want to find the intersection for lines in the picture. Could you please help me!

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Answer 1

darova 2021-3-6

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/764726-how-to-find-intersection-between-lines#answer_640616

use polyxpoly

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Hossein Alishahi 2021-3-6

Thank you for your consideration.

It does not work for fimplicit function which has ploted the lines. Could you please give me more information in specefic codes

Best,

Hossein

darova 2021-3-7

在 MATLAB Online 中打开

use contour to get lines
use polyxpoly to calculate interseciton

clc,clear
[x,y,z] = peaks(30);
[~,h] = contour(x,y,z,[0 0]);
x2 = [-2 3];
y2 = [-3 0];
h1 = get(h,'children');
x1 = get(h1(3),'xdata');            % extract 3d contour
y1 = get(h1(3),'ydata');
[xc,yc] = polyxpoly(x1,y1,x2,y2);   % find intersection
hold on
plot(x1,y1,'.r')
plot(x2,y2,'linewidth',2)
plot3(xc,yc,'or')
hold off