Not enough input arguments error. Help?

function [c,ceq] = constraint(A)
% Define node coordinates (mm)
nod_coor = [(1000*sqrt(3)) 0;0 1000;((2000*sqrt(3))/3) 1000;(1000*(1+sqrt(3))) 1000];

ele_nod = [1 2;1 3;1 4];% Define Elements between nodes

num_ele = size(ele_nod,1);% Number of Elements

num_nod = size(nod_coor,1);% Number of nodes

ele_dof = [1 2 3 4;1 2 5 6;1 2 7 8];% Define element dof

% Define structural properties Area, MoE, Density

E(1) = 70e3; %N/mm^2 for Aluminium
E(2) = 70e3; %N/mm^2 for Aluminium
E(3) = 70e3; %N/mm^2 for Aluminium

% Initialise zero matrix for all matrices
displacement = zeros(2*num_nod,1);
force = zeros(2*num_nod,1);
stiffness = zeros(2*num_nod);

% Apply loads at DOF's (N)
force(1) = 6000.0e3;
force(2) = -10000.0e3;

% Boundary conditions
displacement(3,1) = 0.0;
displacement(4,1) = 0.0;
displacement(5,1) = 0.0;
displacement(6,1) = 0.0;
displacement(7,1) = 0.0;
displacement(8,1) = 0.0;


% Computation of the system stiffness matrix
    for e = 1:num_ele
        % Compute element length
        L(e) = sqrt((nod_coor(ele_nod(e,2),1)-nod_coor(ele_nod(e,1),1))^2+...
        (nod_coor(ele_nod(e,2),2)-nod_coor(ele_nod(e,1),2))^2);
  
        % Compute the (theta) = (xj-xi)/L
        cos = (nod_coor(ele_nod(e,2),1)-nod_coor(ele_nod(e,1),1))/L(e);
        sin = (nod_coor(ele_nod(e,2),2)-nod_coor(ele_nod(e,1),2))/L(e);
    
        % Compute element stiffness matricies
        k = ((A(e)*E(e)/L(e))*[cos*cos  cos*sin -cos*cos -cos*sin; cos*sin sin*sin -cos*sin -sin*sin;...
        -cos*cos -cos*sin cos*cos cos*sin; -cos*sin -sin*sin cos*sin sin*sin]);
    
        % Extract the rows of the ele_dof for each element e 
        % Compute global stiffness matrix
        ele_dof_vec = ele_dof(e,:);
        for i = 1:4 
            for j = 1:4
                stiffness(ele_dof_vec(1,i), ele_dof_vec(1,j))=...
                stiffness(ele_dof_vec(1,i), ele_dof_vec(1,j))...
                + k(i,j);
            end
        end
        
    end

% known force array: input boundery  conditions 
known_f_a = [1;2];
    for i = 1:size(known_f_a,1)
        dis_new(i,1) = displacement(known_f_a(i,1),1);
        force_new(i,1) = force(known_f_a(i,1),1);
    end 
  
    for i = 1:size(known_f_a,1)
        for j  = 1:size(known_f_a,1)
            stiff_new(i,j) = stiffness(known_f_a(i,1),known_f_a(j,1));
        end
    end
    
% Solving the partitoined matrix
dis_new = stiff_new\force_new;

    for i=1:size(known_f_a,1)
        displacement(known_f_a(i,1),1)=dis_new(i,1);
    end

% Known displacement array
known_dis_a = [3;4;5;6;7;8];
    for i = 1:size(known_dis_a,1)
        force(known_dis_a(i,1),1) = stiffness(known_dis_a(i,1),:)...
            *displacement;
    end
    
% stress in elements
    for e = 1:num_ele
         L(e)=sqrt((nod_coor(ele_nod(e,2),1)-nod_coor(ele_nod(e,1),1))^2+...
      (nod_coor(ele_nod(e,2),2)-nod_coor(ele_nod(e,1),2))^2);
        cos=(nod_coor(ele_nod(e,2),1)-nod_coor(ele_nod(e,1),1))/L(e);
        sin=(nod_coor(ele_nod(e,2),2)-nod_coor(ele_nod(e,1),2))/L(e);
        stress(e)=(E(e)/L(e))*[-cos -sin cos sin]*displacement((ele_dof(e,:))');
    end

disp('stiffness')
stiffness
disp('displacement')
displacement
disp('force')
force
disp('stress')
stress' 

k=0;
    for i = 1:num_nod
        for j=1:2
         k=k+1;
           nod_coor_def(i,j)=nod_coor(i,j)+displacement(k,1);
        end
    end


% Determine force's in elements
    for e = 1:num_ele
    F(e) = sqrt(force(ele_dof(e,3))^2+force(ele_dof(e,4))^2)
    end
% Inequlity constraint 

X = [A(1) A(2) A(3)]
c = F-400*X %N/mm2

%Equality constraint 
ceq = []; %no equality constraint
end

This is the error i am recieving. Thanks in advance.

Not enough input arguments.

Error in constraintdom (line 51)

k = ((A(e)*E(e)/L(e))*[cos*cos cos*sin -cos*cos -cos*sin; cos*sin sin*sin -cos*sin -sin*sin;...

[dpb]

Not obvious but aliasing cos() and sin() isn't a wise thing to do. It doesn't look like should cause a problem here, but there's so much code to look at could easily have missed something in visual inspection.

I'd start by making a local variable like cs, sn or something similar in place of cos, sin and then go from there.

Answer 1

[Ameer Hamza]

sin and cos are name of MATLAB built-in functions. You have also created variable with this name. This can create confusion for MATLAB. Change your variable names to something else.