change initial condition with binary data in matlab
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clear all;
close all;
% Constants
M=315; % space domain length (in m)
c=2*pi; % wvae speed constant (300 m/s = 2*pi rad/s)
dx=5.; % grid space interval
nx=round(M/dx)+1; % number of grid in space domain
nk = nx-1; % number of waves in frequency domain
dt = 0.001666; % time step interval
nt=500; % number of time steps
tmax = dt*nt; % maximum time to calculate solution
% Initialization
u(:,1) = zeros(nx,1);
for ix=11:22
xx=(ix-1)*dx;
u(ix,1)=100*(sin(pi*((xx-50)/60)));
end
m = mean(u(:,1)); % k=0 contain the mean of the data, save it for latter
% Second initial condition
uk(:,1) = fft(u(:,1)); % Fourier Transform
uk(:,2) = complex(zeros(nx,1)); % get the Fourier coeff. for next step
for k = 1:nk,
if (k < fix((nk/2))+1),
uk(k+1,2) = (1 - dt*c*1i*(k))*uk(k+1,1);
else
uk(k+1,2) = (1 - dt*c*1i*(-nk-1+k))*uk(k+1,1);
end
end
ut = ifft(uk(:,2)); % Inverse Fourier to get u in space domain
u(:,2) = real(ut)+m; % Add the average to the real part to get u at second step
clear ut;
% Solution using spectral method for all other t
uk(:,3:nt) = complex(zeros(nx,nt-2)); % get the Fourier coeff. for next step
for it = 3:nt,
for k = 1:nk,
if (k < fix((nk/2))+1),
uk(k+1,it) = uk(k+1,it-2) - 2*dt*c*1i*(k)*uk(k+1,it-1);
else
uk(k+1,it) = uk(k+1,it-2) - 2*dt*c*1i*(-nk-1+k)*uk(k+1,it-1);
end
end
ut= ifft(uk(:,it)); % Inverse Fourier to get u in space domain
u(:,it) = real(ut)+m; % Add the average to the real part to get u at the next step
clear ut;
end
% Plotting output
xi =([1:nx])*dx; % x-axis
%x = [-pi+2*pi/nx:2*pi/nx:pi]'; % if wanted, x axis can be changed to -pi < x < pi
plot(xi,u(:,1),'-b','linewidth',2); % Plot the initial condition
hold on;
for it=10:20:nt
plot(xi,u(:,it),'-r'); % Plot the rest of the solution
end
hold off;
grid on;
axis([0 max(xi) -10 110]);
xlabel('X (m)','fontweight','bold');
ylabel('Amplitude','fontweight','bold');
title(['1D Linear Advection for t = ' num2str(tmax) ' seconds'],...
'fontsize',14,'fontweight','bold');
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Respuestas (1)
KALYAN ACHARJYA
el 10 de Nov. de 2019
Editada: KALYAN ACHARJYA
el 10 de Nov. de 2019
"change initial condition with binary data in matlab"
Is this?
Change here
u(:,1)=randi([0 1],nx,1)
And
uk(:,2) =randi([0 1],nx,1)
2 comentarios
KALYAN ACHARJYA
el 10 de Nov. de 2019
I answered based on initialization comment in the code. May be you have to load "u" data from that file.
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