MATLAB Answers

Count the number of intersections between any two curves

조회 수: 23(최근 30일)
SATHYA PRIYA SUGUMAR
SATHYA PRIYA SUGUMAR 2019년 11월 11일
편집: Matt J 2019년 11월 11일
Hi all,
I have two curves and I need to find and count the number of times they intersect. Is there any matlab function to do so?
  댓글 수: 2
SATHYA PRIYA SUGUMAR
SATHYA PRIYA SUGUMAR 2019년 11월 11일
I have two analytical functions.

댓글을 달려면 로그인하십시오.

답변(2개)

Matt J
Matt J 2019년 11월 11일
편집: Matt J 2019년 11월 11일
The only general way (i.e., for arbitrary curves) is using the Symbolic Math Toolbox,
solve(curve1==curve2)

Dimitris Kalogiros
Dimitris Kalogiros 2019년 11월 11일
편집: Dimitris Kalogiros 2019년 11월 11일
If you have two functions y=f(t) and y=g(t) you can find their intersections by solving the equation f(t)=g(t). But such a thing (maybe) should be an impossible task.
So, here you are a more general approach
clearvars;
clc;
syms t f(t) g(t)
%define functions
f(t)=(t^2)+3*sin(2*pi*t)-2
g(t)=exp((1/2)*t)
%plot the functions
fplot(f(t)); hold on;
fplot(g(t));
%refine plot
grid on;
legend('f', 'g');
ax = gca;
ax.YAxisLocation='origin';
ax.XAxisLocation='origin';
%determine intersections
downLimit=-5; upperLimit=5; %area of searching
dt=0.1; % accuracy step (it should be small enough)
rootCounter=0;
h(t)=f(t)-g(t);
for t=downLimit:dt:upperLimit
if h(t)==0 %f(t)=g(t)
rootCounter=rootCounter+1;
elseif h(t)*h(t+dt)<0 % f(to)=g(to), t<to<t+dt
rootCounter=rootCounter+1;
end
end
fprintf('found %d roots', rootCounter);
  댓글 수: 1
Dimitris Kalogiros
Dimitris Kalogiros 2019년 11월 11일
.... and here you are what you get, when you run this code
demo.jpg

댓글을 달려면 로그인하십시오.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by