# how to compute derivative

조회 수: 1 (최근 30일)
Elysi Cochin . 2021년 4월 4일
편집: darova . 2021년 4월 5일 having all the values in the above equation, is the below code correct for dE(t)/d(t) computation?
dEt = beta * (1 - sigma) * St * It - (mu + alpha) * Et
what do i need to do to compute dE(t)/d(t)
##### 댓글 수: 4표시 이전 댓글 수: 3숨기기 이전 댓글 수: 3
John D'Errico 2021년 4월 4일
What you have not said is explicitly WHAT you have.
What does it mean to have values?
is beta a fixed known constant? How about mu and alpha?
Is S known as a function, or do you have a list of points for S as a function of t?
Similarly for I(t). Is that known?
Is E(t) known, or are you trying to solve for E(t). That would make this a differential equation, if E is an unknown function.
Finally, do you have some sort of initial value for E(t) at some fixed value for t?

댓글을 달려면 로그인하십시오.

### 채택된 답변

darova 2021년 4월 5일
Only you know initial conditions. Imagine the situation: you are throwing the ball, initial conditions are velocity and angle. Only you know how you want to throw the ball
YOu should use for loop to get solution for all your values
for i = 1:size(SIE,1) % numer of rows
S = SIE(i,1);
I = SIE(i,2);
E = SIE(i,3);
[t,E] = ode45(@(t,E) myfunc(t,S,I,E),tspan,E);
line(t,E)
end
##### 댓글 수: 2표시 이전 댓글 수: 1숨기기 이전 댓글 수: 1
darova 2021년 4월 5일
편집: darova 님. 2021년 4월 5일
One curve for one set of data. You can't get one curve if you have many values and initial conditions, it's impossible
Imagine you are throwing the bal at different angles but want to get only want trajectory
One angle - one trajectory

댓글을 달려면 로그인하십시오.

### 카테고리

Help CenterFile Exchange에서 Ordinary Differential Equations에 대해 자세히 알아보기

### Community Treasure Hunt

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

Start Hunting!