Finding the intersect between 2 lines
19 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
Hello, very simple question, however, I have tried using multiple methods, such as polyxpoly() from the Mapping Toolbox to find the intersection between these 2 lines, but I cannot see what the issue is. I have just used a simulatneous equation (as shown in the code) to solve for the equation just to get an output as polyxpoly() wasn't returning anything. The y value seems correct, but the x value is widely incorrect.![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/517032/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/517032/image.png)
Here is my code:
xrt = linspace((1/297.7), (1/446.1), 20000)
m11 = -197.7506;
x11 = 0.0031;
b11 = 20.8898;
line1=m11*(xrt-x11)+b11;
plot(xrt, line1, '-')
hold on;
m22 = -897.4321;
x22 = 0.0029'
b22 = 20.9819;
line2=m22*(xrt-x22)+b22;
plot(xrt, line2, '-')
x_intersect = (b22-b11)/(m11-m22) %find the x point
y_intersect = m11*x0+b11
plot(x_intersect,y_intersect,'r*')
The output values for x_intersect and y_intersect:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/517037/image.png)
Any help would be greatly appreciated.
Thanks.
2 commentaires
Rik
le 11 Fév 2021
Actually your math is incorrect, as the y-value is not correct either:
xrt = linspace((1/297.7), (1/446.1), 20000);
m11 = -197.7506;
x11 = 0.0031;
b11 = 20.8898;
line1=@(xrt) m11*(xrt-x11)+b11;
m22 = -897.4321;
x22 = 0.0029';
b22 = 20.9819;
line2=@(xrt) m22*(xrt-x22)+b22;
x_intersect = (b22-b11)/(m11-m22) %find the x point
y_intersect = line2(x_intersect)
plot(xrt, line1(xrt), '-')
hold on;
plot(xrt, line2(xrt), '-')
plot(x_intersect,y_intersect,'r*')
Réponse acceptée
James Tursa
le 11 Fév 2021
Modifié(e) : James Tursa
le 11 Fév 2021
If you want the intersection of two lines and you have the equations of the lines, just use backslash. E.g., if you have these equations:
y = m1*x + b1
y = m2*x + b2
Then your system is equivalently
y - m1*x = b1
y - m2*x = b2
or
[1 -m1;1 -m2]*[y;x] = [b1;b2]
So the intersection point is just
[1 -m1;1 -m2] \ [b1;b2]
You just need to plug in the appropriate m and b values for your two lines.
m1 = m11
b1 = m11*(-x11)+b11;
m2 = m22
b2 = m22*(-x22)+b22;
Plus de réponses (1)
David Hill
le 11 Fév 2021
xrt = linspace((1/297.7), (1/446.1), 20000);
m11 = -197.7506;
x11 = 0.0031;
b11 = 20.8898;
line1=@(x)m11*(x-x11)+b11;
plot(xrt, line1(xrt), '-');
hold on;
m22 = -897.4321;
x22 = 0.0029;
b22 = 20.9819;
line2=@(x)m22*(x-x22)+b22;
plot(xrt, line2(xrt), '-');
A=[1,-m11;1,-m22];
b=[b11-m11*x11;b22-m22*x22];
c=A\b;
plot(c(2),c(1),'g*');
0 commentaires
Voir également
Catégories
En savoir plus sur 2-D and 3-D Plots dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!