Populating a matrix with user input

answer=inputdlg({'nodes'});
nodes=str2double(answer(1,1));
nodematrix=Inf(nodes);
A=1;
B=0;
answer=[];

while A < nodes 
    B = B+1;
    while B < nodes
       B = B+1;
       answer = str2double(inputdlg(['Enter resistance between ',num2str(A),' and ',num2str(B)]));
       nodematrix(A,B) = str2double(answer)
       nodematrix(B,A) = str2double(answer)
    end 
    A = A+1;
    B = 1; 
end 

disp(nodematrix)

OUTPUT:

 Inf   NaN   NaN   NaN   NaN
   NaN   Inf   NaN   NaN   NaN
   NaN   NaN   NaN   NaN   NaN
   NaN   NaN   NaN   NaN   NaN
   NaN   NaN   NaN   NaN   Inf

I was wondering why these are showing up as NaN?? And I also am trying to fill this where it does not ask to fill the diagonal.. The diagonal should always be zero. I don't know why its asking for those values..

Answer 1

[KALYAN ACHARJYA]

See the example:

Get the data from inputdlg;

Say any number 3, 4,5,6 ........

Then

>> str2double(4)
ans =

   NaN

>> str2double(7)

ans =

   NaN

I have removed the str2double in answer statement, str2double convert strings to double precision values, not numeric data

answer=inputdlg({'nodes'});
nodes=str2double(answer(1,1));
nodematrix=nodes6;
A=1;
B=0;
answer=[];
while A < nodes 
    B = B+1;
    while B < nodes
       B = B+1;
       answer =inputdlg(['Enter resistance between ',num2str(A),' and ',num2str(B)]);
       nodematrix(A,B) = str2double(answer)
       nodematrix(B,A) = str2double(answer)
    end 
    A = A+1;
    B = 1; 
end 

##

nodematrix =
     6     5     6     7     8     3
     5     0     6     7     8     2
     6     6     4     7     3     6
     7     7     7     8     5     0
     8     8     3     5     5     6
     3     2     6     0     6     0

[Steven Lord]

I'd call str2double once to create a double variable answer then simply assign that answer into the elements of nodematrix.

answer = str2double(inputdlg(...));
nodematrix(A,B) = answer;
nodematrix(B,A) = answer;

Actually, I'd probably just fill in the upper triangular piece of nodematrix inside the loops (for which you can use nested for loops) then make nodematrix symmetric using triu.

M1 = triu(magic(4))
M2 = M1 + triu(M1, 1).'

But since I suspect this is part of a homework assignment I'll leave it at that hint.

[Emma Sellers]

That worked to get numbers! Can you tell me how to fix it so it doesnt ask about the diagonal? I.e. I don't want (1,1), (2,2), (3,3) to change..

[KALYAN ACHARJYA]

Thank you @Steven