2-D Truss Analysis

I have got my for loop to work which was my main issue but now when I try to display the unit vectors into command window using the fprintf my unit vectors all come out as zero. When I run my for loop they are not zero. I can't seem to figure out what is causing them to be zero in the fprintf

%.... Input problem data
    nNodesP = 12;
    nMembersP = 21;
	NodeP = zeros(nNodesP, 3);		%Initialize memory storage
	MemberP = zeros(nMembersP, 2);
 
%.... Input node coordinates
    NodeP(1,:) = [0,0,0];
    NodeP(2,:) = [2,0,0];
    NodeP(3,:) = [4,0,0];
    NodeP(4,:) = [6,0,0];
    NodeP(5,:) = [8,0,0];
    NodeP(6,:) = [10,0,0];
    NodeP(7,:) = [12,0,0];
    NodeP(8,:) = [10,1.5,0];
    NodeP(9,:) = [8,3,0];
    NodeP(10,:) = [6,3,0];
    NodeP(11,:) = [4,3,0];
    NodeP(12,:) = [2,1.5,0];
    
%.... Input member connections
    MemberP(1,:) = [1,2];
    MemberP(2,:) = [2,3];
    MemberP(3,:) = [3,4];
    MemberP(4,:) = [4,5];
    MemberP(5,:) = [5,6];
    MemberP(6,:) = [6,7];
    MemberP(7,:) = [7,8];
    MemberP(8,:) = [8,9];
    MemberP(9,:) = [9,10];
    MemberP(10,:) = [10,11];
    MemberP(11,:) = [11,12];
    MemberP(12,:) = [1,12];
    MemberP(13,:) = [2,12];
    MemberP(14,:) = [2,11];
    MemberP(15,:) = [3,11];
    MemberP(16,:) = [3,10];
    MemberP(17,:) = [4,10];
    MemberP(18,:) = [5,10];
    MemberP(19,:) = [5,9];
    MemberP(20,:) = [6,9];
    MemberP(21,:) = [6,8];


	
%% .. Use a for loop to compute the position vector between connected 
%nodes, the distance between connected nodes, and to compute the unit
%vectors for the direction of every member.  You can use the variable name
%"UnitVecP" for the unit vectors in the planar truss.

PosVecP = zeros(nMembersP, 3);		%Initialize memory storage
UnitVecP = zeros(nMembersP, 3);
OppPosVecP = zeros(nMembersP, 3);

for j = 1 : nMembersP
        SN = MemberP(j,1);           %SN = start node
        EN = MemberP(j,2);           %EN = end node

        PosVecP(j,:) = NodeP(EN,:)- NodeP(SN,:);
        Length(j,:) = norm(PosVecP(j,:));
        UniVecP(j,:) = PosVecP(j,:)/Length(j,:) 
        negUniVecP(j,:) = -UniVecP(j,:);
        
%Finish this section to compute the position vector, length, unit vector,
%and negative unit vector for each member in the truss.

end		% for j (members)


%% .Create output for command window
      fprintf('%s\n'     ,  '----------------------------------------')
      fprintf('%s\n'     ,  '-------------Planar Truss---------------')
      fprintf('%s\n'     ,  '----------------------------------------')
      for j = 1 : nNodesP
        fprintf('%s%8i%8.3f%8.3f%8.3f\n','   Node: ',j, NodeP(j,:)')
      end
      fprintf('\n')
      for j = 1 : nMembersP
        fprintf('%s%8i%8.3f%8.3f%8.3f\n','   Unit Vector: ',j, UnitVecP(j,:)') 
      end
      fprintf('\n\n\n')

      

[KSSV]

The vectors are zeros.

[Jillian Franke]

How would I go about fixing this issue so they aren't zeros in the display window?

[Long Hoang Van]

boolean matrix?

Answer 1

[Asad (Mehrzad) Khoddam]

One t was missing in UniVctor:

%.... Input problem data
nNodesP = 12;
nMembersP = 21;
NodeP = zeros(nNodesP, 3);		%Initialize memory storage
MemberP = zeros(nMembersP, 2);

%.... Input node coordinates
NodeP(1,:) = [0,0,0];
NodeP(2,:) = [2,0,0];
NodeP(3,:) = [4,0,0];
NodeP(4,:) = [6,0,0];
NodeP(5,:) = [8,0,0];
NodeP(6,:) = [10,0,0];
NodeP(7,:) = [12,0,0];
NodeP(8,:) = [10,1.5,0];
NodeP(9,:) = [8,3,0];
NodeP(10,:) = [6,3,0];
NodeP(11,:) = [4,3,0];
NodeP(12,:) = [2,1.5,0];

%.... Input member connections
MemberP(1,:) = [1,2];
MemberP(2,:) = [2,3];
MemberP(3,:) = [3,4];
MemberP(4,:) = [4,5];
MemberP(5,:) = [5,6];
MemberP(6,:) = [6,7];
MemberP(7,:) = [7,8];
MemberP(8,:) = [8,9];
MemberP(9,:) = [9,10];
MemberP(10,:) = [10,11];
MemberP(11,:) = [11,12];
MemberP(12,:) = [1,12];
MemberP(13,:) = [2,12];
MemberP(14,:) = [2,11];
MemberP(15,:) = [3,11];
MemberP(16,:) = [3,10];
MemberP(17,:) = [4,10];
MemberP(18,:) = [5,10];
MemberP(19,:) = [5,9];
MemberP(20,:) = [6,9];
MemberP(21,:) = [6,8];



%% .. Use a for loop to compute the position vector between connected
%nodes, the distance between connected nodes, and to compute the unit
%vectors for the direction of every member.  You can use the variable name
%"UnitVecP" for the unit vectors in the planar truss.

PosVecP = zeros(nMembersP, 3);		%Initialize memory storage
UnitVecP = zeros(nMembersP, 3);
OppPosVecP = zeros(nMembersP, 3);

for j = 1 : nMembersP
    SN = MemberP(j,1);           %SN = start node
    EN = MemberP(j,2);           %EN = end node
    
    PosVecP(j,:) = NodeP(EN,:)- NodeP(SN,:);
    Length(j,:) = norm(PosVecP(j,:));
    UnitVecP(j,:) = PosVecP(j,:)/Length(j,:);
    negUniVecP(j,:) = -UniVecP(j,:);
    
    %Finish this section to compute the position vector, length, unit vector,
    %and negative unit vector for each member in the truss.
    
end		% for j (members)


%% .Create output for command window
fprintf('%s\n'     ,  '----------------------------------------')
fprintf('%s\n'     ,  '-------------Planar Truss---------------')
fprintf('%s\n'     ,  '----------------------------------------')
for j = 1 : nNodesP
    fprintf('%s%8i%8.3f%8.3f%8.3f\n','   Node: ',j, NodeP(j,:)')
end
fprintf('\n')
for j = 1 : nMembersP
    fprintf('%s%8i%8.3f%8.3f%8.3f\n','   Unit Vector: ',j, UnitVecP(j,:)')
end
fprintf('\n\n\n')

[Jillian Franke]

Thank you!!