Error when trying to use output value of a function in another fucntion

Hello, I am trying to use the output value(w) of a function(simple_LMS1) in another fucntion(simple_LMS2) but it giving error like

Undefined function or variable "w".
Error in simple_LMS2 (line 10)
  y(n) = w'*x1; % filter output
Error in Motion_simple_LMS (line 12)
        [w,y,e,W]=simple_LMS2(x1,x1,0.1,M);

The code I am uisng is

 P=load('Analog_signal.mat');
a2=P.a1;
M=5;
for i=1:500:length(a2)-2000
    if(i<499)
     x1=a2(i:i+499,:);     
        [w,y,e,W]=simple_LMS1(x1,x1,0.1,M);     
    else          
        x1=a2(i:i+499,:); 
        [w,y,e,W]=simple_LMS2(x1,x1,0.1,M);
        pause(0.2);
    end;
end

The simple_LMS1 function is

function [w,y,e,W] = simple_LMS1(x,d,mu_step,M)
N = length(x); % number of data samples
 y = zeros(N,1); % initialize filter output vector
 w = zeros(M,1); % initialize filter coefficient vector
e = zeros(N,1); % initialize error vector
W = zeros(M,N); % filter coefficient matrix for coeff. history
for n = 1:N
  if n <= M % assume zero-samples for delayed data that isn't available
      k = n:-1:1;
      x1 = [x(k); zeros(M-numel(k),1)];
  else
      x1 = x(n:-1:n-M+1); % M samples of x in reverse order
  end
  y(n) = w'*x1; % filter output
  e(n) = d(n) - y(n); % error
  w = w + mu_step*e(n)'*x1; % update filter coefficients
  W(:,n) = w; % store current filter coefficients in matrix
end

Function simple_LMS2 is

function [w,y,e,W] = simple_LMS2(x,d,mu_step,M)
N = length(x); % number of data samples
for n = 1:N
  if n <= M % assume zero-samples for delayed data that isn't available
      k = n:-1:1;
      x1 = [x(k); zeros(M-numel(k),1)];
  else
      x1 = x(n:-1:n-M+1); % M samples of x in reverse order
  end
  y(n) = w'*x1; % filter output
  e(n) = d(n) - y(n); % error
  w = w + mu_step*e(n)'*x1; % update filter coefficients
  W(:,n) = w; % store current filter coefficients in matrix
end

can someone tell me how to solve this error so that I can use 1st function output in the 2nd fucntion.

Answer 1

[Matt J]

In the line

y(n) = w'*x1; % filter output

the variable w is undefined. It was never previously introduced into the workspace of simple_LMS2, either as an input argument or otherwise.

[Gova ReDDy]

But I was trying to use the output w of the simple_LMS1 function. Can I know how to use the output w of the simple_LMS1 in the simple_LMS2 function.

[Matt J]

You should pass w to simple_LMS2() as an additional input argument. Currently, however, simple_LMS2 only accepts 4 input arguments, not 5

x,d,mu_step,M

[Gova ReDDy]

thanks Matt J it is working now.