Error: Too many output arguments

Hello. In my main M script I have:

% X is defined previously - m x 9 array
N = 100;
alpha = zeros(N,1);
lambda = zeros(N, 9); % N x 9 vector - it can be multiplied by X' with getting N x m array
% 2. Function to minimize:
h = Hypothesis(X, T4, alpha, lambda); % 1 x m vector
J = @(alpha, lambda) SCBCost4(X, T4, alpha, lambda, h); % a number (1 x 1)

% 2.1 Partial derivatives:
dJ_alpha = @(alpha, lambda) DerivCost_alpha(X, T4, lambda, h); % N x 1 vector
% dJ_lambda = @(alpha, lambda) DerivCost_lambda(X, T4, alpha, lambda, h); % N x 9 array 
GAMMA = 0.01;    
MAX_ITER = 100;  
FUNC_TOL = 0.1;   
Jvals = [];       
progress = @(iter, alpha, lambda) fprintf('iter = %d: alpha = %s, lambda = %s, J(alpha, lambda) = %f\n', ...
    iter, mat2str(alpha(1),3), mat2str(lambda(1, :),9), J(alpha, lambda));
 
% 3.2 Iterate:
iter = 1;         
Jvals(iter) = J(alpha, lambda);
progress(iter, alpha, lambda);

while iter < MAX_ITER && Jvals(end) > FUNC_TOL
    iter = iter + 1;
    alpha = alpha - GAMMA * dJ_alpha(alpha, lambda);  % HERE I HAVE THE ERROR (N x 1 vector = N x 1 vector - number*[N x 1 vector])
    % lambda = lambda - GAMMA * dJ_lambda(alpha, lambda);
    Jvals(iter) = J(alpha, lambda);    
    progress(iter, alpha, lambda);      % show progress
end

In function 'DerivCost_alpha' I have:

function dJ_alpha = DerivCost_alpha(X, y, lambda, h)

N = 100;
m = length(y);
h = Hypothesis (X, y, alpha, lambda); % 1 x m vector
s = zeros(N, m); % N x m array
for n = 1:N
    s(n, :) = sin(lambda(n, :)*X'); % 1 x m vector. N of such vectors form the N x m array
end
dJ_alpha = zeros(N, 1);
for n = 1:N
    for j = 1:m
        dJ_alpha(n, :) = dJ_alpha(n, :) + (1/m)*((h(j) - y(j))*s(n, i));
    end
end

In function 'Hypothesis' I have:

function h = Hypothesis(X, y, alpha, lambda)

N = 100;
m = length(y);
S = zeros(N, m); % N x m array
for n = 1:N
    S(n, :) = (alpha(n))*sin((lambda(n, :))*X'); % 1 x m vector. N of such vectors form the N x m array
end
h = zeros(1, m); 
for i = 1:m
    h(i) = sum(S(:, i)); % summing elements in each column of array S. Get 1 x m vector
end
  
end

When I run it I get the next:

>> iter = 1: alpha = 0, lambda = [0 0 0 0 0 0 0 0 0], J(alpha, lambda) = 1426.354673

Error using alpha

Too many output arguments.

Error in DerivCost_alpha (line 5)

h = Hypothesis (X, y, alpha, lambda);

Error in Draft2>@(alpha,lambda)DerivCost_alpha(X,T4,lambda,h) (line 23)

dJ_alpha = @(alpha, lambda) DerivCost_alpha(X, T4, lambda, h);

Why could this error happen? I can't really understand. Please, help.

Thanks for reading!

[Adam Danz]

The error message says it all.

The function you're calling has 1 output.

function dJ_alpha = DerivCost_alpha(X, y, lambda, h)

but you're asking for two outputs

dJ_alpha = @(alpha, lambda) DerivCost_alpha(X, T4, lambda, h); % N x 1 vector
%            ^^^^^  ^^^^^^