Questions tagged [ode45]
140 questions
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Solving nonlinear system of differential equations in matlab usin ODE45
i am trying to solve a system of nonlinear differential equation using ODE45 MATLAB , i did that many times successfully , but this time i get the following error and i really don't know what is wrong i am confused compeletly. here are the codes.
%%…
ayhan
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Solving Delayed Differential Equations using ode45 Matlab
I am trying to solve DDE using ode45 in Matlab. My question is about the way that I am solving this equation. I don't know if I am right or I am wrong and I should use dde23 instead.
I have a following equation:
xdot(t)=Ax+BU(t-td)+E(t) &…
Sina
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Passing variables into a function used in ODE solver inside PARFOR
I have a ODE function which I am trying to solve multiple times with different parameters.
here is the function
function xdot=SB(t,x)
global ps f R0
S=.0725 ;
rhoL=998;
vL =1.0e-3;
c = 1481;
pvtinf=0 ;
pinf0=1.01e5;
k =7/5;…
Hos
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MATLAB ODE45: only saving last solution
I would like to only have ODE45 retain the last solution. Rather returning the all the solutions from the tspan = [t0 tf]; I only want the returned vector to be the solution at tf.
The reason why I would like to do this is to avoid the following…
kirikoumath
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How to debug this Matlab code to model glider descent?
I have this Matlab project but for some reason I just cannot stop thinking about it because I could not get it to work.
Objective:
This is a MATLAB script that would calculate the change of pressure, temperature and density of a glider that is being…
Gadless
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ODE45 which i can not solve
I have a problem to use ODE45. I gave the matlab code below. I can not start the solver. Probably it is a syntax error. If you can find the problem i would be happy.
It is a modeling and simulation of packed bed reactor. However; i get errors before…
hksdejavu
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Error when passing arguments to function handles
Suppose we have the following function:
function f=lorenz(t,x,a,b,c)
% solve differential equation like this
%dx/dt=a*(y-x)
%dy/dt=-x*z+b*x-y
%dz/dt=xy-c*z/3
f=zeros(3,1);% preallocate result
f(1)=a*(x(2)-x(1));
…
user466534
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In MATLAB ode45, how do I solve a system of ODE where a parameter is dependent on other parameter, and not time dependant?
Consider the equations for a launch vehicle
dv/dt = T/m - D/m - g*sin(gam)
v*d(gam)/dt = -g(-v^2/W)*cos(gam) where W is a constant
dh/dt = v*sin(gam).
Where v represents velocity, T is thrust.
My thrust values are discrete, hence i have to use…
Vin
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increase speed by decreasing the number of operating digits in ODE45
I am working with ODE45 and I want to force matlab to only operate with as much as 2 decimals.
I have seen that is possible to do that with vpa, but it is not really working in the ODE. Any ideas?
Thank you!
kumbu
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How to set the RHS when using ode45 in matlab if I have to use some parameter which depends on the solution in each time step?
y(1)' = y(2);
y(2)' = [-y(1)-y(2)^2]/(y(1)+C0);
y(3)' = y(3)/y(4)*y(2)*C1;
y(4)' = y(2)*FF;
C0, C1, C2 and C3 are Const., FF is C2*y(3)^0.5 if y(3) > 100; FF is C3*y(3)^0.5 if y(3)<=100.
How to set y(4)' in this situation?
I tried y(4)' =…
Ben
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MATLAB ode45 function 'Too many inputs error'
My function is:
function [tout, yout] = Lorenz (rho, x0)
%define constants
sigma = 10;
beta = 8/3;
%initial conditions
y0 = [x0; 1; 0];
f = @(t, y) [sigma*(y(2)-y(1)); (y(1)*(rho-y(3)))-y(2); (y(1)*y(2)) - (beta*y(3))];
[tout, yout] = ode45(f, [0…
Sriram Iyer
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Matlab: ODE45+Shooting Method appear to be not working
I am trying to solve numerically three simultaneous ODE functions:
dw/ds = sin(theta)
dx1/ds = cos(theta)
dtheta/ds = - a * cos(theta) * (w-w0) + a * sin(theta) * x1
I am solving for a column which is separated in two halves, I want to plot w…
dan.ABQ
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Matlab ode45 is not outputting solutions for each increment specified by my "time-span" vector
I am using the following code to call a function for ODE45 to solve:
[outputs]=ode45(@(t,y)ILLYAcoupled(t,y,N,w,g),(0:0.5e-3:50),y0);
I am trying to get ode45 to give me values at 0.5e-3 increments between 0 and 50, which should output a solution…
zek3r
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Matlab ode45 internal step
I'm having doubts at how to use ode45 since I know it uses an internal variable step size. For instance, in my particular case I have a model of ODE's and I use a sampling time of 5 minutes. Hence, inside my main simulation loop I have the following…
Aleo
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MATLAB Plot depending Variable in ode
I've a problem in MATLAB. I try to plot a variable inside the ode function. I call my ode Funktion with this code:
%Above is the code for the IC and constants
%Initial conditions [x0, vx0, y0, vy0]
IC = [x_0; w_x; y_0;…
R.Ugolini
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