How to find the intersection values of line and curve?

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GULZAR
GULZAR 2023-8-29
回答： Bruno Luong 2023-8-29
Ran in:
How to find the intersection values of line(black) and the curve(blue). And I need the intersection points in ascending order in array. Can you please help.....
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This is a program for 1-D Photonic crystal
% For Photonic band structure calculation and Transmission Spectrum
% This program uses Transfer Matrix Method
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
clc
clear all
close all
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Initialization of parameters
dB=7778e-9; % Thickness of Second Layer
dA=0.1*5303e-9; % Thickness of First Layer
nA=3.3; % Refractive index of First Layer
nB=2.25; % Refraive index of Second Layer
n0=1; % Refractive index of Incident and transmission medium
c=3e8; % Velocity of Light (m/s)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Frequency Range
frequncy=0.1:0.1:40; % Frequncy in THz
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for loop=1:length(frequncy)
% angular frequency
w=2*pi*frequncy*1e12;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
d=dA+dB; DA=((w(loop))/c)*dA*nA; DB=((w(loop))/c)*dB*nB;
m11=cos(DA); m12=-1i*sin(DA)/nA; m21=-1i*nA*sin(DA); m22=cos(DA); mA=[m11 m12; m21 m22];
l11=cos(DB); l12=-1i*sin(DB)/nB; l21=-1i*nB*sin(DB); l22=cos(DB); mB=[l11 l12; l21 l22];
m=(mA*mB);
RHS(loop)=(m(1,1)+m(2,2))/2;
end
plot(frequncy,RHS)
hold on
yline(-1)
yline(1)
hold off
  4 个评论
显示 2更早的评论
Dyuman Joshi
Dyuman Joshi 2023-8-29
"Here i'm using for loop."
That does not make any difference.
You can still apply the method suggested in that answer.
"I'm confusing to use that previous method. "
How are you confused?
Bruno Luong
Bruno Luong 2023-8-29
If you are confused the iI recommend asking specific question focusing on what confuses you, instead of ignoring it and ask again the same question. You'll end of with a tone of things that confuse you even after 10 year of MATLAB practicing.

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采纳的回答

Bruno Luong
Bruno Luong 2023-8-29
Ran in:
OK I'll be nice with you because of your laziness I just copy the solution of another thread here; wirh a little adaptation to sort them
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This is a program for 1-D Photonic crystal
% For Photonic band structure calculation and Transmission Spectrum
% This program uses Transfer Matrix Method
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%clc
%clear all <====== BAD programming practice
%close all
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Initialization of parameters
dB=7778e-9; % Thickness of Second Layer
dA=0.1*5303e-9; % Thickness of First Layer
nA=3.3; % Refractive index of First Layer
nB=2.25; % Refraive index of Second Layer
n0=1; % Refractive index of Incident and transmission medium
c=3e8; % Velocity of Light (m/s)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Frequency Range
frequncy=0.1:0.1:40; % Frequncy in THz
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for loop=1:length(frequncy)
% angular frequency
w=2*pi*frequncy*1e12;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
d=dA+dB; DA=((w(loop))/c)*dA*nA; DB=((w(loop))/c)*dB*nB;
m11=cos(DA); m12=-1i*sin(DA)/nA; m21=-1i*nA*sin(DA); m22=cos(DA); mA=[m11 m12; m21 m22];
l11=cos(DB); l12=-1i*sin(DB)/nB; l21=-1i*nB*sin(DB); l22=cos(DB); mB=[l11 l12; l21 l22];
m=(mA*mB);
RHS(loop)=(m(1,1)+m(2,2))/2;
end
allyx = [-1 1];
xintersect = [];
yintersect = [];
for yx = allyx
ys = RHS-yx;
i = find(ys(1:end-1).*ys(2:end) <= 0);
% linear interpolation
i1 = i; ss1 = ys(i1);
i2 = i1 + 1; ss2 = ys(i2);
w = ss2./(ss2-ss1);
xx = w.*frequncy(i1) + (1-w).*frequncy(i2);
yy = yx+zeros(size(xx));
xintersect = [xintersect, xx];
yintersect = [yintersect, yy];
end
[xintersect, is] = sort(xintersect);
yintersect= yintersect(is);
figure
plot(frequncy,RHS)
hold on
yline(allyx)
plot(xintersect, yintersect, 'or')
hold off

更多回答（1 个）

Rawad SADAH
Rawad SADAH 2023-8-29
Try this code
% Finding intersection points
threshold = 0.01; % Adjust this threshold based on your data and precision needs
intersection_points = [];
for loop = 2:length(frequncy)
if (RHS(loop) > -1 && RHS(loop - 1) < -1) || (RHS(loop) < 1 && RHS(loop - 1) > 1)
% Perform linear interpolation to find the approximate intersection point
t = (1 - RHS(loop - 1)) / (RHS(loop) - RHS(loop - 1));
intersection_freq = frequncy(loop - 1) + t * (frequncy(loop) - frequncy(loop - 1));
% Add the intersection point to the array
intersection_points = [intersection_points, intersection_freq];
end
end
% Sort the intersection points in ascending order
sorted_intersection_points = sort(intersection_points);
disp("Intersection Points:");
disp(sorted_intersection_points);
% Plotting the intersection points on the blue curve
hold on;
plot(sorted_intersection_points, ones(size(sorted_intersection_points)), 'ro');
hold off;

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