get the following error message when I have have a variable QUEUE
and then for i:2500, I loop through QUEUE(i). I don't understand why
Matlab is attempting to access QUEUE(-2.14748e+009)....Can anyone
help me with this error? I suspect it might be a floating point
problem, is it possible?
----------------------

??? Attempted to access QUEUE(-2.14748e+009); index must be a
positive integer or logical.

Error in ==> CompBNodeMeas at 15
QUEUE(i)=0;
--------------------------

The strange thing is that it doesn't happen every time. Sometimes I get the error, sometimes the program executes till completion.

Any help would be greatly appreciated.

Nobody can help you if they can't see the source code.

Nobody can help you if they can't see the source code.

The source code is appended below. Many apologies and really appreciate any help from anyone.
--------------------------------------
for i=1:50
Bcount(i)=0;
end

% start considering node k as head
for k=1:50

%initialize queue
index=1; %index points to the current empty cell on QUEUE
for i=1:(50*50)
QUEUE(i)=0;
end

%reset level values
for i=1:50
Level(i)=0;
end
%set level for k as -1
Level(k)=-1;

%reset anc matrix
for i=1:50
for j=1:50
anc(i,j)=0;
end
end

%look for vertices adjacent to k
for n=1:50
if A(k,n)==1 %A(k,n) is 1 if vertex k is adjacent to n
%put n on QUEUE and shift index
QUEUE(index)=n;
index=index+1;
%set n on level 1
Level(n)=1;
%put n on its own anc list
anc(n,n)=1;
end
end

while index~=1
% pop the first vertex from QUEUE
r=QUEUE(1);

for n=1:50
if ((n~=k)&(A(r,n)==1)&(Level(n)==Level(r)+1)) %if n has been visited before
for i=1:50
if anc(r,i)~=0
Bcount(i)=Bcount(i)+anc(r,i);
end
end
for i=1:50
anc(n,i)=anc(n,i)+anc(r,i);
end
if anc(r,r)>=2
anc(n,n)=anc(n,n)+anc(r,r);
else
anc(n,n)=anc(n,n)+1;
end
end

if((n~=k)&(A(r,n)==1)&(Level(n)==0)) %if n has not been visited before
%put n on QUEUE and shift index
QUEUE(index)=n;
index=index+1;
%set n's level
Level(n)=Level(r)+1;

for i=1:50
if anc(r,i)~=0
Bcount(i)=Bcount(i)+anc(r,i);
end
end
for i=1:order
anc(n,i)=anc(n,i)+anc(r,i);
end
if anc(r,r)>=2
anc(n,n)=anc(n,n)+anc(r,r);
else
anc(n,n)=anc(n,n)+1;
end
end
end

%shift entries in QUEUE and adjust index
for i=1:(index-1)
QUEUE(i)=QUEUE(i+1);
end
index=index-1;
end %end popping nodes from QUEUE

end %end considering all nodes k as head
-------------------------