Runge Kutta Loop and save array of results to workspace

8 vues (au cours des 30 derniers jours)
Komal Rajana
Komal Rajana le 8 Juil 2020
Commenté : Komal Rajana le 8 Juil 2020
Hello,
I would like to run the runge kutta method within a loop for various values for 'p'. My problem is saving the array of results (for outputs=Y) in the workspace for each loop/increment of 'p'. Please assist. Thank you
function [x, y] = FunctionBeta_Executor(F)
for p=1:0.2:5
h=0.15; % step size (smaller step size gives more accurate solutions)
x = 0:h:3; % x space
y = zeros(length(x):1); % Memory allocation
y(1) = 0; % initial condition
F = @(x, y)(x+y+p);
for i=1:(length(x)-1)
% i=1:(length(x)-1) % calculation loop
k1 = F(x(i),y(i));
k2 = F(x(i)+0.5*h,y(i)+0.5*h*k1);
k3 = F((x(i)+0.5*h),(y(i)+0.5*h*k2));
k4 = F((x(i)+h),(y(i)+k3*h));
y(i+1) = y(i) + (1/6)*(k1+2*k2+2*k3+k4)*h; % main equation
end
figure, plot(x, y) % To see the solution results
end
end

Réponse acceptée

Alan Stevens
Alan Stevens le 8 Juil 2020
Here's one way:
p=1:0.2:5;
h=0.15;
x = 0:h:3;
y = zeros(length(x),length(p));
F = @(x, y, p)(x+y+p);
for j=1:length(p)
y(1,j) = 0; % initial condition
for i=1:(length(x)-1)
k1 = F(x(i),y(i,j), p(j));
k2 = F(x(i)+0.5*h, y(i,j)+0.5*h*k1, p(j));
k3 = F((x(i)+0.5*h), y(i,j)+0.5*h*k2, p(j));
k4 = F((x(i)+h), y(i,j)+k3*h, p(j));
y(i+1,j) = y(i,j) + (1/6)*(k1+2*k2+2*k3+k4)*h; % main equation
end
end
figure, plot(x, y) % To see the solution results

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