Reference to non-existent field 'xd'. Kindly help .

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utsav kakkad
utsav kakkad 2018-11-19
编辑： Stephen23 2018-11-19
I am working on a network protocol & I seem to be getting stuck at a point with the error "Reference to non-existent field 'xd'.".
the code I'm working on is as follows : -
clc
clear all;
close all;
%message size in bits
l=2000;
%field dimensions
xm=300;
ym=300;
%sink = center of the field
sink.x=0.5*xm;
sink.y=0.5*ym;
%number of sensor nodes
n=250;
%probability of a node to be elected cluster head
p=0.1;
%initial energy
Eo=0.5;
ETX=50*0.000000001;
ERX=50*0.000000001;
Eelec=ETX;
%transmit amplifier types
Efs=10e-12;
Emp=0.0013e-12;
%data aggregation energy
EDA=5*0.000000001;
%the maximum number of rounds
rmax=250;
do=sqrt(Efs/Emp);
%optimum number of cluster heads
k=20;
t=0;
Et=0;
for h=1:1
S(n+1).xd=sink.x;
S(n+1).yd=sink.y;
Et=0;
for i=1:1:n
S(i).xd=rand(1,1)*xm;
XR(i)=S(i).xd;
S(i).yd=rand(1,1)*ym;
YR(i)=S(i).yd;
%distance between each sensor node & the cluster head
distance=sqrt( (S(i).xd-(S(n+1).xd) )^2 + (S(i).yd-(S(n+1).yd) )^2 );
S(i).distance=distance;
S(i).G=0;
%initially there are no cluster heads only nodes
S(i).type='N';
S(i).E=Eo;
Et=Et+S(i).E;
figure(h*10)
plot(S(i).xd,S(i).yd,'bo');
text(S(i).xd+1,S(i).yd-0.5,num2str(i));
hold on;
end
%plotting the cluster head
plot(S(n+1).xd,S(n+1).yd,'o', 'MarkerSize', 12, 'MarkerFaceColor', 'r');
text(S(n+1).xd+1,S(n+1).yd-0.5,num2str(n+1));
hold off ;
countCHs=0; %variable, counts the cluster head
cluster=1; %cluster is initialized as 1
flag_first_dead=0; %flag tells the first node dead
flag_half_dead=0; %flag tells the 10th node dead
flag_all_dead=0; %flag tells all nodes dead
first_dead=0;
half_dead=0;
all_dead=0;
allive=n;
%counter for bit transmitted to Bases Station and to Cluster Heads
packets_TO_BS=0;
packets_TO_CH=0;
packets_TO_BS_per_round=0;
for r=0:1:rmax
r
packets_TO_BS_per_round=0;
%Operations for epochs
if(mod(r, round(1/p) )==0)
for i=1:1:n
%every node is initialized to not belonging to a cluster and
%having 0 G value in the beginning
S(i).G=0;
S(i).cl=0;
end
end
%hold off;
%Number of dead nodes
dead=0;
for i=1:1:n
%counting the number of nodes with non zero G value
if (S(i).G > 0)
t = t + 1;
end
%checking if there is a dead node
if (S(i).E<=0)
%plotting dead nodes
plot(S(i).xd,S(i).yd,'red .');
dead=dead+1;
if (dead==1)
if(flag_first_dead==0)
%first dead node useful in calculating the network
%lifetime
first_dead=r;
flag_first_dead=1;
end
end
if(dead==0.5*n)
if(flag_half_dead==0)
half_dead=r;
flag_half_dead=1;
end
end
if(dead==n)
if(flag_all_dead==0)
all_dead=r;
flag_all_dead=1;
end
end
%hold on;
end
if S(i).E>0
S(i).type='N';
end
end
%plotting the sink/base station
plot(S(n+1).xd,S(n+1).yd,'x');
STATISTICS.DEAD(h,r+1)=dead;
STATISTICS.ALLIVE(h,r+1)=allive-dead;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
countCHs=0;
cluster=1;
for i=1:1:n
%Cluster Head election process if the node has energy/normal
%node/alive node
if(S(i).E>0)
temp_rand=rand;
if ( (S(i).G)<=0)
%new Cluster Head will be elected when G value falls below0
if ( t < k)
if ( t > 0)
while (countCHs < t)
countCHs = countCHs + 1;
packets_TO_BS=packets_TO_BS+1;
packets_TO_BS_per_round=packets_TO_BS_per_round+1;
PACKETS_TO_BS(r+1)=packets_TO_BS;
S(i).type='C';%CH election
S(i).G=round(1/p)-1;
C(cluster).xd=S(i).xd;
C(cluster).yd=S(i).yd;
plot(S(i).xd,S(i).yd,'dr');
end
if(t==0 & S(i).type~='C')
S(i).G = round(1/p)-1;
end
%electing k-t cluster heads
while(countCHs<k-t)
countCHs=countCHs+1;
packets_TO_BS=packets_TO_BS+1;
packets_TO_BS_per_round=packets_TO_BS_per_round+1;
PACKETS_TO_BS(r+1)=packets_TO_BS;
S(i).type='C';
S(i).G=round(1/p)-1;
C(cluster).xd=S(i).xd;
C(cluster).yd=S(i).yd;
plot(S(i).xd,S(i).yd,'dr');
end
end
else
while(countCHs<t)
countCHs=countCHs+1;
packets_TO_BS=packets_TO_BS+1;
PACKETS_TO_BS(r+1)=packets_TO_BS;
S(i).type='C';
S(i).G=round(1/p)-1;
plot(S(i).xd,S(i).yd,'dr');%plots cluster heads with red diamonds
C(cluster).xd=S(i).xd;
C(cluster).yd=S(i).yd;
plot(S(i).xd,S(i).yd,'k*');
d=sqrt( (S(i).xd-(S(n+1).xd) )^2 + (S(i).yd-(S(n+1).yd) )^2 );
C(cluster).distance=d;
C(cluster).id=i;
X(cluster)=S(i).xd;
Y(cluster)=S(i).yd;
cluster=cluster+1;
end
end
distance=sqrt( (S(i).xd-(S(n+1).xd) )^2 + (S(i).yd-(S(n+1).yd) )^2 );
C(cluster).distance=distance;
C(cluster).id=i;
X(cluster)=S(i).xd;
Y(cluster)=S(i).yd;
cluster=cluster+1;
%Calculation of Energy dissipated
distance;
if (distance>=do)
S(i).E=S(i).E- ( (Eelec)*(l) + Emp*l*( distance*distance*distance*distance ));
end
if (distance<do)
S(i).E=S(i).E- ( (Eelec)*(4000) + Efs*l*( distance * distance ));
end
end
end
end
end
STATISTICS.COUNTCHS(h,r+1)=countCHs;
% or STATISTICS.COUNTCHS(h,r+1)=clster-1;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Election of Associated Cluster Head for Normal Nodes
for i=1:1:n
if ( S(i).type=='N' && S(i).E>0 )
if(cluster-1>=1)
min_dis=sqrt( (S(i).xd-S(n+1).xd)^2 + (S(i).yd-S(n+1).yd)^2 );
min_dis_cluster=0;
for c=1:1:cluster-1
temp=min(min_dis,sqrt( (S(i).xd-C(c).xd)^2 + (S(i).yd-C(c).yd)^2 ) );
if ( temp<min_dis )
min_dis=temp;
min_dis_cluster=c;
end
end
if(min_dis_cluster~=0)
min_dis;
if (min_dis>=do)
S(i).E=S(i).E- ( Eelec*(l) + Emp*l*( min_dis * min_dis * min_dis * min_dis));
end
if (min_dis<do)
S(i).E=S(i).E- ( Eelec*(l) + Efs*l*( min_dis * min_dis));
end
S(C(min_dis_cluster).id).E = S(C(min_dis_cluster).id).E- ( (ERX + EDA)*l );
packets_TO_CH=packets_TO_CH+1;
else
min_dis;
if (min_dis>=do)
S(i).E=S(i).E- ( ETX*(l) + Emp*l*( min_dis * min_dis * min_dis * min_dis));
end
if (min_dis<do)
S(i).E=S(i).E- ( ETX*(l) + Efs*l*( min_dis * min_dis));
end
packets_TO_BS=packets_TO_BS+1;
packets_TO_BS_per_round=packets_TO_BS_per_round+1;
PACKETS_TO_BS(r+1)=packets_TO_BS;
end
S(i).min_dis=min_dis;
S(i).min_dis_cluster=min_dis_cluster;
else
min_dis=sqrt( (S(i).xd-S(n+1).xd)^2 + (S(i).yd-S(n+1).yd)^2 );
if (min_dis>=do)
S(i).E=S(i).E- ( Eelec*(l) + Emp*l*( min_dis * min_dis * min_dis * min_dis));
end
if (min_dis<do)
S(i).E=S(i).E- ( Eelec*(l) + Efs*l*( min_dis * min_dis));
end
packets_TO_BS=packets_TO_BS+1;
packets_TO_BS_per_round=packets_TO_BS_per_round+1;
end
end
end
STATISTICS.PACKETS_TO_CH(h,r+1)=packets_TO_CH;
STATISTICS.PACKETS_TO_BS(h,r+1)=packets_TO_BS;
STATISTICS.PACKETS_TO_BS_PER_ROUND(h,r+1)=packets_TO_BS_per_round;
STATISTICS.THROUGHPUT(h,r+1)=STATISTICS.PACKETS_TO_BS(h,r+1)+STATISTICS.PACKETS_TO_CH(h,r+1);
En=0;
for i=1:n
if S(i).E<=0
continue;
end
En=En+S(i).E;
end
ENERGY(r+1)=En;
STATISTICS.ENERGY(h,r+1)=En;
end
first_dead_LEACH(h)=first_dead
half_dead_LEACH(h)=half_dead
all_dead_LEACH(h)=all_dead
for r=0:rmax
STATISTICS.DEAD(h+1,r+1)=sum(STATISTICS.DEAD(:,r+1))/h;
STATISTICS.ALLIVE(h+1,r+1)=sum(STATISTICS.ALLIVE(:,r+1))/h;
STATISTICS.PACKETS_TO_CH(h+1,r+1)=sum(STATISTICS.PACKETS_TO_CH(:,r+1))/h;
STATISTICS.PACKETS_TO_BS(h+1,r+1)=sum(STATISTICS.PACKETS_TO_BS(:,r+1))/h;
STATISTICS.PACKETS_TO_BS_PER_ROUND(h+1,r+1)=sum(STATISTICS.PACKETS_TO_BS_PER_ROUND(:,r+1))/h;
STATISTICS.THROUGHPUT(h+1,r+1)=sum(STATISTICS.THROUGHPUT(:,r+1))/h;
STATISTICS.COUNTCHS(h+1,r+1)=sum(STATISTICS.COUNTCHS(:,r+1))/h;
STATISTICS.ENERGY(h+1,r+1)=sum(STATISTICS.ENERGY(:,r+1))/h;
end
first_dead=sum(first_dead_LEACH)/h;
half_dead=sum(half_dead_LEACH)/h;
all_dead=sum(all_dead_LEACH)/h;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
r=0:rmax;
figure(1)
plot(r,STATISTICS.DEAD(h+1,r+1));
title('dead nodes')
figure(2)
plot(r,STATISTICS.ALLIVE(h+1,r+1));
title('live nodes')
figure(3)
plot(r,STATISTICS.PACKETS_TO_BS(h+1,r+1));
title('pkts to BS')
figure(4)
plot(r,STATISTICS.PACKETS_TO_BS_PER_ROUND(h+1,r+1));
title('pkts to BS per round')
figure(5)
plot(r,STATISTICS.PACKETS_TO_CH(h+1,r+1));
title('pkts to CH')
figure(6)
plot(r,STATISTICS.THROUGHPUT(h+1,r+1));
title('THROUGHPUT')
figure(7)
plot(r,STATISTICS.COUNTCHS(h+1,r+1));
title('COUNTCHS')
figure(8)
plot(r,STATISTICS.ENERGY(h+1,r+1));
title('Average Residual Energy')
Now I am getting the error in line 216, temp=min(min_dis,sqrt( (S(i).xd-C(c).xd)^2 + (S(i).yd-C(c).yd)^2 ) );
Please note that this isn't the first time I am using S(i).xd, I have used it before also.
I am stumped. Please help. Just guide me towards the correct syntax/usage.
I am out of touch with matlab.

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采纳的回答

Stephen23
Stephen23 2018-11-19
编辑：Stephen23 2018-11-19
The problem is related to structure C, not structure S.
The fields xd and yd of structure C are defined inside while loops whose conditions are never true on the 250th iteration of the r loop, thus you do not define those fields. This pretty easy to check: just run the code until the error occurs, then check the values in the workspace:
>> h
h = 1
>> i
i = 1
>> r
r = 250
>> C
C =
1x250 struct array containing the fields:
distance
id
>> countCHs
countCHs = 0
>> t
t = 0
>> k
k = 20
It is quite clear that the conditions, e.g.:
while (countCHs < t)
are not met, so those while loops don't run.

更多回答（1 个）

Alan Weiss
Alan Weiss 2018-11-19
The problem isn't S(i).xd, it is C(c).xd that doesn't exist. Your structure C(c) has fields distance and id but not xd.
Alan Weiss
MATLAB mathematical toolbox documentation

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