how with ode45 order we can solve a switching problem?

조회 수: 1 (최근 30일)
azam ghamari
azam ghamari 2019년 7월 29일
댓글: Stephan 2019년 8월 1일
Hi every one.
I want to write a code like this with ode45. how can I do it?
ode45(func)
func:
mode 1;
if x>=550
mode =2;
if mode=2 and x<=510
mode=1;
x'=f(x)= 0.1*x-50 mode =1
0.1*x-56 mode=2
I write this code, but gives me not correct output in figure
clc;
clear all;
close all;
deltat=10^-2;
x1(1)=510;
x11(1)=550;
for i=1:1000
x1(i+1)=(0.1*x1(i)-50)*deltat+x1(i);
y1(i)=x1(i);
if x1(i+1)>=550 && x1(i+1)==(0.1*x1(i)-50)*deltat+x1(i)
%return i;
x1(i+1)=(0.1*x1(i)-56)*deltat+x1(i);
y1(i)=x1(i);
elseif x1(i+1)<=510 && x1(i+1)==(0.1*x1(i)-56)*deltat+x1(i)
%return i;
x1(i+1)=(0.1*x1(i)-50)*deltat+x1(i);
y1(i)=x1(i);
end
end
figure(1)
plot(i,y1(i))
And what may I do to ruturn "i" as index when "x" reaches 550 or 510?
writing the above code "return i" it gives this error:
Error: File: ntest.m Line: 12 Column: 16
Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax
error. To construct matrices, use brackets instead of parentheses.
Thanks

답변 (2개)

Stephan
Stephan 2019년 7월 29일
  댓글 수: 4
azam ghamari
azam ghamari 2019년 7월 31일
Hi, Two days ago I answered you, that I actually read it and I don't know how shall I use the odeXY. please see my answer in below.
and may you please write that code (that I wrote with ode45) with ODEXY?
Thanks and Best Reagards.
Stephan
Stephan 2019년 8월 1일
At the moment im on vacation and have no access to my computer.

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azam ghamari
azam ghamari 2019년 7월 30일
I see it , but I am not sure to undrestand some parts for example:
isterminal(i) = 1 if the integration is to terminate when the ith event occurs. Otherwise, it is 0.
what does it mean exactly?
and I write the code without ode:
clc;
clear all;
close all;
deltat=1;
x1(1)=510;
x11(1)=550;
x1(2)=(0.1*x1(1)-50)*deltat+x1(1);
for i=1:1000
y1(i)=x1(i);
if (x1(i+1)>=550 && x1(i+1)==(0.1*x1(i)-50)*deltat+x1(i))||(x1(i+1)<=550 && x1(i+1)==(0.1*x1(i)-56)*deltat+x1(i))
%return i;
x1(i+2)=(0.1*x1(i+1)-56)*deltat+x1(i+1);
y1(i)=x1(i);
elseif (x1(i+1)<=510 && x1(i+1)==(0.1*x1(i)-56)*deltat+x1(i))||(x1(i+1)>=510 && x1(i+1)==(0.1*x1(i)-50)*deltat+x1(i))
%return i;
x1(i+2)=(0.1*x1(i+1)-50)*deltat+x1(i+1);
y1(i)=x1(i);
end
end
figure(1)
plot(x1)
Iand it gives me the result, and I want to write teh code with ode function , how can I change my before code taht I sent befor (with ode) based on this code in away that I get the result ?(with odeXY that you introduced)
Thanks

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