How to create nested for loops that has two changing variables to output one variable?
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Alyssa Mills
el 4 de Dic. de 2018
Comentada: Alyssa Mills
el 4 de Dic. de 2018
This is the code I am trying to run, and I am unsure how to write nested for loops to run over a certain time period and length.
Context: I am trying to find what the function will look like after the time ends and how r and hz evolve. Ultimately I will want to plot the r and hz together.
%Intial Conditions
rho=(3.6*30*24*60*60); %3.6 months
u=10^9;
u0=2*10^-5;
v=1*10^6;
r0=2000; %Intial radius
h0=180; %Intial height
V=(3/4)*pi()*(r0^2)*h0; %volume
v0=1*10^6;
g=1.31;
tau=((3/4)^5)*(((pi()^3)*v0*(r0^8))/(g*V^3));
%% Theta
for t=1:172800; %Using the time for 2 days
theta(t)=rho*(1-exp(-t/rho));
end
%% Solving function
for r=1:3000;
for ta=1:theta;
hz(r,ta)=(((4*V)/(3*pi()*r0^2)).*(1./((1+(ta./tau)).^1/4)).*(1-(((r.^2)./(r0^2)).*(1./(1+((ta./tau).^1/4))))).^(1/3));
end
end
3 comentarios
Walter Roberson
el 4 de Dic. de 2018
Your code already tests different angles (ta) and different radii (r ) . If you want to test different tau as well you would add another loop and probably add another index on the output.
Respuesta aceptada
Walter Roberson
el 4 de Dic. de 2018
rho=(3.6*30*24*60*60); %3.6 months
u=10^9;
u0=2*10^-5;
v=1*10^6;
r0=2000; %Intial radius
h0=180; %Intial height
V=(3/4)*pi()*(r0^2)*h0; %volume
v0=1*10^6;
g=1.31;
tau=((3/4)^5)*(((pi()^3)*v0*(r0^8))/(g*V^3));
%% Theta
for t=1:172800; %Using the time for 2 days
theta(t)=rho*(1-exp(-t/rho));
end
%% Solving function
hz = zeros(3000, length(theta));
for r=1:3000;
for ta=1:length(theta);
hz(r,ta)=(((4*V)/(3*pi()*r0^2)).*(1./((1+(theta(ta)./tau)).^1/4)).*(1-(((r.^2)./(r0^2)).*(1./(1+((theta(ta)./tau).^1/4))))).^(1/3));
end
end
This is rather slow and you should try to vectorize it.
9 comentarios
Walter Roberson
el 4 de Dic. de 2018
tvals = [2, 27, 3.6*365/12, 1.5*365] * 24 * 60 * 60; %seconds
rvals = 1 : 3000;
rho=(3.6*30*24*60*60); %3.6 months
u=10^9;
u0=2*10^-5;
v=1*10^6;
r0=2000; %Intial radius
h0=180; %Intial height
V=(3/4)*pi()*(r0^2)*h0; %volume
v0=1*10^6;
g=1.31;
tau=((3/4)^5)*(((pi()^3)*v0*(r0^8))/(g*V^3));
%% Theta
for tidx = 1 : length(tvals)
theta(tidx)=rho*(1-exp(-tvals(tidx)/rho));
end
%% Solving function
hz = zeros(3000, length(theta));
for ridx = 1 : length(rvals)
r = rvals(ridx);
for tidx = 1:length(theta)
ta = theta(tidx);
hz(r,tidx)=(((4*V)/(3*pi()*r0^2)).*(1./((1+(ta./tau)).^1/4)).*(1-(((r.^2)./(r0^2)).*(1./(1+((ta./tau).^1/4))))).^(1/3));
end
end
subplot(1,2,1)
plot(rvals, real(hz))
legend(sprintfc('%g', tvals/(24*60*60)))
subplot(1,2,2)
plot(rvals, imag(hz))
legend(sprintfc('%g', tvals/(24*60*60)))
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