Multiple outputs from a function in a for loop

I'm trying to get multiple outputs from a function in a for loop, and am instead getting multiple columns of the same output. The function within the for loop gives me the correct output when I run the function once (with two different output variables), but does not give the correct output when nested in the for loop.

Here's the code:

function [e, s] = stressstrain(Nodes, u, MatSet, ElmConnect)

[r,c] = size(ElmConnect);

e = zeros(r, 1);
s = zeros(r, 1);

for b = 1:r

      %define the nodes and material set for each element

      node1_no = ElmConnect(b,1);
      node2_no = ElmConnect(b,2);
      mat_set_no = ElmConnect(b,3);

       % define the variables needed to run barstiffness.m

      node1 = Nodes(node1_no,:);
      node2 = Nodes(node2_no,:);
      modulus = MatSet(mat_set_no,1);

      % find nodal displacements per node coordinates

      u1 = u(node1_no,:);
      u2 = u(node2_no,:);

      % run bar stress/strain for each element and add to global system

      [E, S] = barstressstrain(node1, u1, node2, u2, modulus);

      e(b) = E;
      s(b) = S;

end
end

And here's the second function barstressstrain:

function [e, s] = barstressstrain(node1, u1, node2, u2, modulus)

% original element length

diff = node2-node1;
L = sqrt(diff(1)^2 + diff(2)^2 + diff(3)^2);

Cx = (node2(1) - node1(1)) / L;
Cy = (node2(2) - node1(2)) / L;
Cz = (node2(3) - node1(3)) / L;

% using the formula given in Logan textbook...

U = [u1' ; u2'];
C = [-Cx -Cy -Cz Cx Cy Cz];

s = (modulus / L) * C * U;

e = s/modulus;

end

When I run this barstressstrain.m for the first element (should be the first row of the matrix results from stresstrain.m, I get the output [-0.5, -2.5]. When I run the function stressstrain.m, the output of the first row is [-0.5, -0.5]. Why am I getting only the first variable for both columns?

Any help is appreciated!

Answer 1

[Matt J]

Assuming you fed the same input data to barstreesstrain in both cases, I can see no reason why they'd be different. However, we have no way of verifying that that's what you did!

[Sarah]

I did feed the same input into both. I would give the numbers I input but its generated from a master function that includes 5 other functions (whose outputs have all been checked). But from the code that is there, you cannot see any reason why it would only be returning one output of the function?

[Matt J]

Nope.

Just give us the direct inputs to barstressstrain, i.e., set a breakpoint at the line

 [E, S] = barstressstrain(node1, u1, node2, u2, modulus);

and when the code stops there, inspect and give us the values of node1, u1, node2, u2, modulus.