CODEWITHSUNDEEP
matlabfunctionmathanonymous-functionnested
tackoo
tackoo

Reputation: 33

Trying to make anonymous function, inside an anonymous function in MATLAB

Hi there this might me a very noob question but I'm stuck, and I'm trying to do this for a while, please help me.

I'm trying to do something like this:

a=0.5;
ODE= @(x,y) ((-2*(a^2)*x*y)/(x^2+y^2)^2)/(1-((a^2)*(x^2-y^2)/(x^2+y^2)^2));


%The classical RK4 solution as a function
k1 = ODE(x,y);
k2 = ODE(x+0.5*dx,y+k1*0.5*dx);
k3 = ODE(x+0.5*dx,y+k2*0.5*dx);
k4 = ODE(x+dx,y+k3*dx);
rk4= @(x,y,dx) y + 1/6*(k1 + 2*(k2+k3) + k4)*dx;

So I first define ODE as an anonymous function then I'm trying to define k's from the ODE and finally RK4 from k's.

But this doesn't work. Any suggestion what to do?

Upvotes: 1

Views: 964

Answers (1)

user57368
user57368

Reputation: 5765

Your k1 through k4 are not being defined or used as functions. When you declare k1 = ODE(x,y), this tries to evaluate the ODE function with vectors x and y that aren't defined. What you probably mean to say is :

k1 = @(x,y,dx) (ODE(x,y));
k2 = @(x,y,dx) (ODE(x+0.5*dx,y+k1(x,y,dx)*0.5*dx));
k3 = @(x,y,dx) (ODE(x+0.5*dx,y+k2(x,y,dx)*0.5*dx));
k4 = @(x,y,dx) (ODE(x+dx,y+k3(x,y,dx)*dx));
rk4= @(x,y,dx) (y + 1/6*(k1(x,y,dx) + \
                2*(k2(x,y,dx)+k3(x,y,dx)) + \
                k4(x,y,dx))*dx);

Upvotes: 2

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