why do I always receive the error: Unrecognized function or variable 'Pt'.

1 次查看（过去 30 天）

显示更早的评论

LoCi 2023-1-5

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1888742-why-do-i-always-receive-the-error-unrecognized-function-or-variable-pt

评论： LoCi 2023-1-9

function [Cout,iter_time] = PGM_opt(Pt,Hdir,H1,H2,maxIter,Qinit,myomegaunitball,c)

17 个评论
显示 15更早的评论隐藏 15更早的评论

LoCi 2023-1-5

编辑：Voss 2023-1-6

在 MATLAB Online 中打开

% Function that implements the PGM iterative optimization
function [Cout,iter_time] = PGM_opt(Pt,Hdir,H1,H2,maxIter,Qinit,myomegaunitball,c)
% Load the initial covariance matrix and RIS phase shifts  
myomegaunitcirc = myomegaunitball.';
Q = Qinit; 
% Line-search parameters 
delta = 1e-5;       
rho = 0.5;
iIter = 0;         
stepsize = 10000;   % Inital step size 
Cout = [RIScap(Hdir,H2,H1,myomegaunitcirc,Q)]; % Initial achievable rate 
Cprev = Cout;
iter_time = 0;
tic
while iIter<maxIter
    iIter = iIter+1;
    q_Q = gracov(Hdir,H2,H1,myomegaunitcirc,Q);     % gradient w.r.t. Q
    g_RIS = gradRIS(Hdir,H2,H1,myomegaunitcirc,Q);  % gradient w.r.t. RIS
    
    for iLineSearch = 0:30
        
        % Updated covariance (Q) matrix, line 3 of Algorithm 1 
        Qnew = Q + stepsize*q_Q;
        Qnew = cov_mat_proj_modified(Qnew,Pt*c^2);
        
        % Updated RIS phase shifts, line 4 of Algorithm 1
        yunitcirc = myomegaunitcirc + stepsize*g_RIS;
        myomegaunitcircnext = projectontounitcircle(yunitcirc)/c;
        
        % New achievable rate 
        Cnew = RIScap(Hdir,H2,H1,myomegaunitcircnext,Qnew);
        
        % Line-search procedure
        if (((Cnew-Cprev) >= delta*(norm(Qnew-Q)^2+ ...
                norm(myomegaunitcircnext-myomegaunitcirc)^2)) ...
                || (stepsize<1e-4) )
            % If the step size satisfies (35c) OR it is too small:    
            % Obtained Q matrix and RIS phase shifts
            myomegaunitcirc = myomegaunitcircnext;
            Q = Qnew;
            Cprev = Cnew;
            break
        else 
            % Reduce the step size 
            stepsize=stepsize*rho;
        end
    end
    % New achievable rate
    Cout = [Cout Cnew];
    % Exection time of an iteration
    iter_time = [iter_time toc];
end
end
% Calculation of gradient w.r.t. Q
function y = gracov(Hdir,H2,H1,myomega,Q)
Z = Hdir+H2*diag(myomega)*H1;
Nr = size(H2,1);
y = Z'*inv(eye(Nr)+Z*Q*Z')*Z;
end
% Calculation of gradient w.r.t. RIS
function y = gradRIS(Hdir,H2,H1,myomega,Q)
Z = Hdir+H2*diag(myomega)*H1;
Nr = size(H2,1);
y = diag(H2'*inv(eye(Nr)+Z*Q*Z')*Z*Q*H1');
end
% Achievable rate calculation
function y = RIScap(Hdir,H2,H1,myomega,Q)
Z = Hdir+H2*diag(myomega)*H1;
Nr = size(H2,1);
y = real(log(det(eye(Nr)+Z*Q*Z')))/log(2);
end
% RIS projection
function y = projectontounitcircle(x)
y = x./abs(x);
end
% Covarinace matrix projection
function Qnew = cov_mat_proj_modified(Qold,Pt)
[U,D] = eig(Qold);
Dnew = water_fill(Pt,real(diag(D))).';
Qnew = U*diag(Dnew)*U';
end 
% Water-filling algorithm
function vect_out = water_fill(Pt,vect_in)
vect_in = vect_in.';
[sort_val,sort_idx] = sort(vect_in,'descend');
for n = length(vect_in):-1:1
    water_level = (sum(sort_val(1:n))-Pt)/n;
    di = sort_val(1:n)-water_level;
    if di(:)>=0
        break
    end   
end
vect_out = zeros(1,length(vect_in));
vect_out(sort_idx(1:n)) = di;
end 

LoCi 2023-1-6

编辑：Voss 2023-1-6

在 MATLAB Online 中打开

clear; close all; clc;
Nt = 8;                 % Number of TX antennas
Nr = 4;                 % Number of RX antennas
Nris = 15^2;            % Number of RIS elements
K = 1;                  % Rician factor    
D = 500;                % TX-RX distance
dist_ris = 40;          % RIS distance from TX
f = 2e9;                % Frequency
lt = 20;                % TX position 
lr = 100;               % RX position 
Pt = 1;                 % Transmit power in Watts
N0 = -120;              % Noise power in dB
SNR = db2pow(-N0);      % SNR            
no_mat = 10;            % Number of channel realizations 
no_iter = 500;          % Number of iterations 
alpha_dir = 3;          % FSPL exponent of the direct link
% Generate channel matrices (WORNING: It is only works for Nris that is a square number)
[Hdirt,H1t,H2t] = chan_mat_RIS_surf_univ_new(Nt,Nr,Nris,lt,lr,D,no_mat,K,f,dist_ris,alpha_dir);
Cpgm = zeros(1,no_iter+1);
for i = 1:no_mat 
    Hdir = Hdirt{i}; H1 = H1t{i}; H2 = H2t{i};                  
    
    % Scaling factor
    c = sqrt(norm(Hdir)/norm(H2*H1))*max(sqrt(Pt),1)/sqrt(Pt)*10;     
    
    % Initial Q matrix and RIS phase shifts    
    Qinit = eye(Nt)*(Pt/Nt);
    omega_init = ones(1,Nris);
    
    % PGM iterative optimization 
    [dCpgm,~] = PGM_opt(Pt,Hdir*sqrt(SNR)/c,H1*sqrt(SNR),H2,no_iter,Qinit*c^2,omega_init/c,c);
    Cpgm = Cpgm+dCpgm;
    
end
semilogx(1:length(Cpgm),Cpgm/no_mat,'r','DisplayName','PGM');
xlabel('Iteration number'); ylabel('Achievable rate [bit/s/Hz]');
xlim([0 no_iter]); 
legend('show','Location','SouthEast');
print('../results/Achievable_Rate', '-dpdf')

LoCi 2023-1-6

编辑：Voss 2023-1-6

在 MATLAB Online 中打开

function [Hdir,H1,H2] = chan_mat_RIS_surf_univ_new(Nt,Nr,Nris,lt,lr,D,no_mat,K,f,dist_ris,varargin)
lambda = 3e8/f;     % Wavelength
dt = lambda/2;      % TX antenna space
dr = lambda/2;      % RX antenna space
dris = lambda/2;    % RIS element space
k = 2*pi/lambda;    % Wavenumber
% Geometrical placement
% x, y and z axis 
% TX antenna array
tx_arr(1,:) = zeros(1,Nt); 
tx_arr(2,:) = (sort(0:Nt-1,'descend')-(Nt-1)/2)*dt+lt; 
tx_arr(3,:) = zeros(1,Nt); 
% RX antenna array
rx_arr(1,:) = D*ones(1,Nr);
rx_arr(2,:) = (sort(0:Nr-1,'descend')-(Nr-1)/2)*dr+lr; 
rx_arr(3,:) = zeros(1,Nr);
% RIS 
center = [dist_ris 0]; % RIS center position 
N1 = sqrt(Nris);
N2 = N1;                                    % Number of RIS elements in two dimensions N1 and N2
ris_pos = RISPosition(N1,N2,dris,center);   % RIS elements' coordinates 
a = repmat(ris_pos{1},N1,1);                % Placing RIS elements in proper coordinates
ris_arr(1,:) = a(:)';        
ris_arr(2,:) = zeros(1,Nris);
ris_arr(3,:) = repmat(ris_pos{2},1,N2); 
if isempty(varargin)                        % Load the FSPL of the direct link
    alpha = 2;
else
    alpha = varargin{1};
end
% direct TX-RX paths/channel matrix
for i1 = 1:Nr                                        % Distance between the TX and RX antennas                                           
    for j1 = 1:Nt
        d(i1,j1) = norm(rx_arr(:,i1)-tx_arr(:,j1));
    end 
end
Hdir_los = exp(-1i*k*d);                             % Direct link, LOS matrix exponents 
tx_rx_dist = sqrt(D^2+(lt-lr)^2);                    % TX-RX distance   
FSPL_dir = (lambda/(4*pi))^2/tx_rx_dist^alpha(1);    % Inversion of the FSPL of the direct link 
Hdir = Rician(Hdir_los,sqrt(FSPL_dir),no_mat,K);     % Direct link channel matrix           
% indirect paths (TX-RIS-RX)
for l1 = 1:Nris                                      % Distance between the RIS elements and the RX antennas                                                            
    for r1 = 1:Nr  
        d2(r1,l1) = norm(rx_arr(:,r1)-ris_arr(:,l1)); 
    end
    for t1 = 1:Nt                                    % Distance between the RIS elements and the TX antennas                  
        d1(l1,t1) = norm(tx_arr(:,t1)-ris_arr(:,l1));   
    end
end
tx_ris_dist = sqrt(dist_ris^2+lt^2);                 % TX-RIS distance
ris_rx_dist = sqrt((D-dist_ris)^2+lr^2);             % RIS-RX distance   
FSPLindir = lambda^4/(256*pi^2)*...                  % Inversion of the FSPL of the indirect link 
    ((lt/tx_ris_dist+lr/ris_rx_dist)^2)*...
    1/(tx_ris_dist*ris_rx_dist)^2;
% TX-RIS channel matrix
H1_los = exp(-1i*k*d1);                             % TX-RIS link, LOS matrix exponents  
FSPL_1 = sqrt(FSPLindir);                           % FSPL of the indirect link is embedded in the TX-RIS channel matrix 
H1 = Rician(H1_los,FSPL_1,no_mat,K);
% RIS-RX channel matrix
H2_los = exp(-1i*k*d2);                             % RIS-RX link, LOS matrix exponents 
FSPL_2 = 1;
H2 = Rician(H2_los,FSPL_2,no_mat,K);
end
function pos = RISPosition(N1,N2,dist,center)                 % Determine positions of RIS elements
d1 = (0:N1-1)-(N1-1)/2;
d2 = (0:N2-1)-(N2-1)/2;
pos{1} = center(1)+d1*dist;
pos{2} = center(2)+d2*dist;
end 
function Hout = Rician(Hlos,FSPL,no_mat,K)                     % Create the Rician channel matices
Hlos = repmat(Hlos,no_mat,1);
Hnlos = sqrt(1/2)*(randn(size(Hlos))+1i*randn(size(Hlos)));
Htot = FSPL/sqrt(K+1)*(Hlos*sqrt(K)+Hnlos);
dim = size(Hlos,1)/no_mat;
for ind = 1:no_mat
    Hout{ind} = Htot((ind-1)*dim+1:ind*dim,:); 
end
end

Voss 2023-1-8

在 MATLAB Online 中打开

@SAFA AWAD: Jan is correct; that's how you can do it in MATLAB.

An alternative would be to go into your operating system's File Explorer and create the folder, e.g., on Windows right-click and select 'New Folder' and rename it 'results'.

The point is that the folder has to exist before you try to write a pdf file in it.

Or you can change where the pdf file should go, e.g., to put in the working directory:

print('Achievable_Rate','-dpdf')

LoCi 2023-1-9