ODE with Newton method
7 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
I am trying to solve the ODE y'=x*cos(x^2)*y^2 using newton's method but my code keeps running forever.
Please, I really appreciate some help with this.
clear all
close all
n=1001
y0=1;
xmin=0; xmax=10;
x=linspace(xmin,xmax,n); %grid
step=(xmax-xmin)/n; %Step Size
yy=zeros(1,n); %Array for results for EEE
yy(1) = y0; % Initial value
%Define the Function and derivative
f=@(x,y) x*cos(x^2)*y^2;
df=@(x,y) 2*x*cos(x^2)*y ;
F=@(x,y,yn) y-yn-step*f(x,y); %Function to set to zero
J=@(x,y) 1 - step*df(x,y); %Jacobian
tol=1.e-5; % Tolerance
for i=xmin+1:n-1
yy(i+1)=yy(i); %initial guess for Newton's method
res=-J(yy(i+1))\F(yy(i+1),yy(i));
while (norm(res,inf)>1.e-10)
yy(i+1)=yy(i+1) + res;
res=-J(yy(1,1))\F(yy(i+1),yy(i));
end
yy(i+1)= yy(i+1) + res;
end
plot(x,yy,'k--')
xlabel('t')
ylabel('y')
Thanks
1 Kommentar
Torsten
am 15 Sep. 2022
For comparison:
fun = @(x,y)x*cos(x^2)*y^2;
n = 1001;
xmin=0; xmax=10;
x=linspace(xmin,xmax,n); %grid
y0 = 1;
[X,Y] = ode45(fun,x,y0);
plot(X,Y)
Antworten (1)
VBBV
am 15 Sep. 2022
Bearbeitet: VBBV
am 15 Sep. 2022
clear all
close all
n=1001
y0=1;
xmin=0; xmax=10;
x=linspace(xmin,xmax,n); %grid
step=(xmax-xmin)/n; %Step Size
yy=zeros(1,n); %Array for results for EEE
yy(1) = y0; % Initial value
%Define the Function and derivative
f=@(x,y) x*cos(x^2)*y^2;
df=@(x,y) 2*x*cos(x^2)*y ;
F=@(x,y,yn) y-yn-step*f(x,y) %Function to set to zero
J=@(x,y) 1 - step*df(x,y) %Jacobian
tol=1.e-5; % Tolerance
for i=xmin+1:n-1
yy(i+1)=yy(i); %initial guess for Newton's method
res=-J(yy(i+1),x(i))\F(x(i),yy(i+1),yy(i)); % why missing input arguments ???
while (norm(res,inf)>1.e-10)
yy(i+1)=yy(i+1) + res;
res=-J(yy(1,1),x(i))\F(x(i),yy(i+1),yy(i));
end
yy(i+1)= yy(i+1) + res;
end
plot(x,yy,'k--')
xlabel('t')
ylabel('y')
0 Kommentare
Siehe auch
Kategorien
Mehr zu Ordinary Differential Equations finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!

