I am having trouble trying to maintain the loop
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Nt=161224;
dt=6e-12;
T=9.6734e-7;
Nz=8061;
Q=2.3131e-6;
dz=0.0012;
N=8061;
n=1.45;
gammaE=0.8967;
Z0=376.7343;
A=8e-11;
z=0:dz:(dz*N-dz);
c=3e8;
G=255.747;
Gth=21;
So basically I am trying ti solve this coupled PDE's , here I have defined ELt as 8061x8061 matrix where time increments is along rows and space along clumns .The program solves for each time iteration and I am trying to save all the values in the matrix.The problem arises when index=8061 and for 8062 it should go to the first row bit I am unable to figure it out. The program just says index array is exceeded. Can anyone help with this loop...
q= 1.7125e07;
eps0=8.854e-12;
Omega=1.207e11;
sigma=826.2189;
GAMMAb=3.5904e8;
Nt1=round(Nt/20);
%t = Nt*dt;
t = (-T/2/dt:1:T/2/dt)*dt;
%fs=1/dbt;
fsine = 1e9;
vsine = 1;
phi = vsine*sin(2*pi*fsine*t);
%% initial conditions
EL1t=1.5607e7*exp(1i*phi);
%EL1t=El_s(1)*ones(1,round(Nt));
ELt=zeros(Nt1,Nz);
ESt=zeros(Nt1,Nz);
ELnew=zeros(1,Nz);
ESnew=ELnew;
%roh=sqrt(n*Q/c/GAMMAb)*(randn(1,Nz)+1i*randn(1,Nz));
%roh=2/GAMMAb*sqrt(Q*GAMMAb/L)*(randn(1,Nz)*(1+1i));
%roh1=2/GAMMAb*sqrt(Q*GAMMAb/L)*(randn(1,Nz)*(1+1i)); %roh value for previous time instant
roh1 = wgn(1,Nz,Q/dt/dz,'complex','linear')*2/(GAMMAb);
roh2=roh1; %roh value for current time instant
%
%% Numerical Process
for index=1:Nt
%ELt(1)=EL1t(index);
ELnew(1)=EL1t(index); %EL(0,t)=ELoexp(i*phi)
Elz=(ELt(index,2:end)-ELt(index,1:end-1))/dz;
ELnew(2:end)=ELt(index,2:end)+dt*c/n*(1i*sigma*roh2(2:end).*ESt(index,2:end)-Elz);%final equation for EL
Esz=(ESt(index,2:end)-ESt(index,1:end-1))/dz;
croh=conj(roh2);
ESnew(1:end-1)=ESt(index,1:end-1)+dt*c/n*(1i*sigma*croh(1:end-1).*ELt(index,1:end-1)+Esz); %final equation for ES
%f=sqrt(n*Q/dt^2/c)*(randn(1,Nz)*(1+1i));
%f =sqrt((Q*GAMMAb)/L)*(randn(1,Nz)+1i*randn(1,Nz));
f =wgn(1,Nz,Q/dt/dz,'complex','linear');
%rohnew=roh+dt*p; this and below equations are for second order
%pnew=p+dt*((-GAMMAb+2*1i*Omega)*p+1i*Omega*GAMMAb*roh+eps0*gammaE*q^2*ELt.*conj(ESt)-2*1i*Omega*f);
%rohnew=roh+dt*(-GAMMAb/2*roh+1i*LAMBDA*ELt.*conj(ESt)+f); the equation is for first order equation(ignoring GAMMAb)
rohnew=1/(1/dt+GAMMAb-2*1i*Omega)*(-roh1/dt+roh2*(2/dt+GAMMAb-2*1i*Omega+1i*GAMMAb*Omega*dt)+dt*(gammaE*eps0*q^2*ELt(index,:).*conj(ESt(index,:))-2*1i*Omega*f));
ELt(index,:)=ELnew;
ESt(index,:)=ESnew;
roh1=roh2;
roh2=rohnew;
%p=pnew;
% % % Plotting the longitudial ntensities for following the process
if (mod(index,5000)==0)
if G<Gth
subplot(2,1,1);
plot (z,2*n/Z0*A*abs(ELt).^2);
hold on
%I_L=2*n/Z0*A*abs(El_s).^2;
legend('Dynamic','Steady State')
hold off
title(['Iteration Number: ',num2str(index)])
xlabel('z [m]'); ylabel('I_L [Watt]');
subplot(2,1,2);
plot (z,2*n/Z0*A*abs(ESt).^2);
hold on
legend('Dynamic','Steady State')
ylabel('I_S [Watt]'); xlabel('z [m]');
else
subplot(2,1,1);
plot (z,2*n/Z0*A*abs(ELt).^2)
hold on
%plot(z,I_L)
legend('Pump Dynamic','Pump Steady State')
hold off
title(['Iteration Number: ',num2str(index),' of ' num2str(Nt)])
xlim([-1 11]); %ylim([-2 inf]);
xlabel('z [m]'); ylabel ('Optical Power')
subplot(2,1,2);
plot (z,2*n/Z0*A*abs(ESt).^2)
hold on
% plot(z,I_S)
legend('Stokes Dynamic','Stokes Steady State')
title(['Iteration Number: ',num2str(index),' of ' num2str(Nt)])
xlim([-1 11]); %ylim([-2 inf]);
xlabel('z [m]'); ylabel ('Optical Power')
%figure;
%plot(z,2*n/Z0*A*abs(ELt).^2);
end
hold off
drawnow;
end
end
if G<Gth
subplot(2,1,1);
end
title('Intensity distibution along the fiber');
2 Kommentare
Stephen23
am 9 Apr. 2024
"The program just says index array is exceeded. Can anyone help with this loop..."
Here are the relevant lines of code:
Nt=161224;
...
Nt1=round(Nt/20);
...
ELt=zeros(Nt1,Nz);
...
for index=1:Nt
...
Elz=(ELt(index,2:end)-ELt(index,1:end-1))/dz;
So you preallocate an array ELT with 8601 rows. But your loop iterates from 1 to 161224, thus throwing an error when you try to access row 8602 (which does not exist).
"The problem arises when index=8061 and for 8062 it should go to the first row bit I am unable to figure it out"
It is unclear exactly what you mean, but perhaps you could use a modulo operation, e.g.:
idx = 1+mod(index-1,Nt1)
Elz = (ELt(idx,2:end)-ELt(idx,1:end-1))/dz;
Antworten (1)
VBBV
am 9 Apr. 2024
Bearbeitet: VBBV
am 9 Apr. 2024
@Yogesh when array sizes dont match , those errors occur. check the array dimensions in for loop
Nt=161224;
dt=6e-12;
T=9.6734e-7;
Nz=8061
Q=2.3131e-6;
dz=0.0012;
N=8061;
n=1.45;
gammaE=0.8967;
Z0=376.7343;
A=8e-11;
z=0:dz:(dz*N-dz);
c=3e8;
G=255.747;
Gth=21;
q= 1.7125e07;
eps0=8.854e-12;
Omega=1.207e11;
sigma=826.2189;
GAMMAb=3.5904e8;
%t = Nt*dt;
t = (-T/2/dt:1:T/2/dt)*dt
%fs=1/dbt;
fsine = 1e9;
vsine = 1;
phi = vsine*sin(2*pi*fsine*t);
%% initial conditions
Nt1=round(Nt/20)
EL1t=1.5607e7*exp(1i*phi);
%EL1t=El_s(1)*ones(1,round(Nt));
ELt=zeros(Nt1,Nz); % the size of this array 8061 x 161224
ESt=zeros(Nt1,Nz); % the size of this array 8061 x 161224
ELnew=zeros(1,Nt); % here the size needs to be checked
ESnew=ELnew;
% in your code
for index = 1:1000:Nt
ELt(index,:)=ELnew; % Here the value of index exceeds the 8061 ...iterates upto 161224
ESt(index,:)=ESnew;
end
ELnew=zeros(Nt1,1);
% change needed for array size match
for index = 1:1000:Nt
ELt(:,index)=ELnew; % Here the value of index exceeds the 8061
ESt(:,index)=ESnew;
end
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