# Solving ODEs using matlab (ode45)

조회 수: 18(최근 30일)
Pazzo Giampalo 2013년 7월 19일
답변: SANDEEP KUMAR R 2016년 9월 14일
Hello,
I am new to matlab. I was trying to follow an instruction from mit.edu.
I want to use ode45 to solve ODEs.
I have the following in my function page:
function dxy = diffxy (t, xy)
x = xy(1);
xdot = xy(2);
y = xy(3);
xdot = xdot;
ydot = 3*x+5;
xdoubledot = 3-ydot+2*xdot
dxy = [xdot; xdoubledot; ydot]
To get a solution, I type [T, XY] ode45 ('diffxy', 0, 10, [0 1 0]) in my command window (t from 0 to 10 and the initial value of x is 0, xdot is 1, and ydot is 0). But the following message :
??? [T, XY] ode45 ('diffxy', 0 10, [0 1 0])
|
Error: Unexpected MATLAB expression.
Thankyou!
Pazzo
##### 댓글 수: 1표시숨기기 없음
Jan 2013년 7월 20일
편집: Jan 2013년 7월 20일
What is "my function page"?
You need an additional "=" to assign the output.

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### 답변(3개)

Matt Kindig 2013년 7월 19일
Did you forget the assignment sign?
[T, XY] = ode45 ('diffxy', 0 10, [0 1 0])
##### 댓글 수: 2표시숨기기 이전 댓글 수: 1
Jan 2013년 7월 20일
Please explain "didn't work" with details. And we have to know, where you have written the shown code.

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Pazzo 2013년 8월 3일
Jan,
I found out that I should add a bracket, [ ],along with an equal sign, =, to make it work.
thank you for your help though.
Pazzo
##### 댓글 수: 0표시숨기기 이전 댓글 수: -1

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SANDEEP KUMAR R 2016년 9월 14일
Instead of 'diffxy' use @diffxy in ode45

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