Undefined function or variable

Hello im stuck and keep getting the Error:

Undefined function or variable 'newtraphlab5'.

Error in Lab5hw (line 18)
[root,iter,ea] = newtraphlab5(func,dfunc,Vo); % obtain the
result

here is my Lab5hw.m

% The van der waals equation relates the pressure, volume and temperature
% use Newton Raphson method to find the root

clc;clear; % Clearing the Command Window and Workspace
% Setting the parameters
n = 1; % number of moles
p = 100.00; % Pressure
T = 300.0; % temperature
a = 1.360; % The unknown constant
b = 0.003183; % The unknown constant
R = 0.0820578; % The gas constant
Vo = 0.246; % Initial guess
% The function to find the root
func = @(V) (p+(n.^2*a)/(V.^2)).*(V-n*b)-n*R*T; % The Ven der Waals equation
% The derivative of the function to find the root
dfunc = @(V) (a*n.^2*(2*b*n-V))./(V.^3)+p; % The derivative of Ven der Waals equation
% Call the function to get the root
[root,iter,ea] = newtraphlab5(func,dfunc,Vo); % obtain the result
% Display the results
fprintf('Volume of one mole of Oxygen = %f\n',root);
fprintf('Number of iterations taken to get the resut = %d\n',iter);
fprintf('Percentage Error = %e\n',ea);

here is my newtraphlab5.m*

function [root,iter,ea] = newtraph(func,dfunc,xr,es,maxit)
% Inputs:
%       
%    
%    
% Outputs:
%      
if nargin<5          % if number of arguments is less then 5 then max is set to 50 
maxit=50;         % sets the max interactions =50
end  
if nargin<4         % if number of arguments less then 4 then st step size .01 
es=0.01;           % step size .01 
end   
iter = 0;           % iteration set to 0
while (1)           % while loop for 1 
      xrold = xr;        % sets the old gas to xr so we can change it later on and run through multiple iterations
       xr = xr - func(xr)/dfunc(xr);   % this is the formula for the newtraph

          iter = iter + 1;       % takes our iteration and adds one to the original to use as the next gues point

          if xr~=0        % if then 
     ea = 100*abs((xr-xrold)/xr);   % fiding the error 
    xrv(iter) = xr; %root vector storing to grab values later 
      eav(iter) = ea; %error vector storing to grab values later 
      inerv(iter) = iter; %iteration vector storing to grab values later 
            end
          if ea <= es || iter >= maxit     % if error is greater or equal if true then set interations lessthen or equal to maxit. if not then stop   
  break        % stopes statements from being executed after this point 
  end
        end
        root = double(xr); 
        subplot(2,1,1) % subplot makes it able to print multiple graphs on 1 window has 2 rows 1 column and 1 Position 
  plot(inerv,xrv)% plots with x,y axis
  xlabel('iteration'); %label x
  ylabel('root estimate'); %label y

subplot(2,1,2)% subplot makes it able to print multiple graphs on 1 window has 2 rows 1 column and 2 Position
plot(inerv,eav)% plots with x,y axis
xlabel('iteration'); %label x
ylabel('Error'); %labely
end

Answer 1

[Walter Roberson]

You have

[root,iter,ea] = newtraphlab5(func,dfunc,Vo); % obtain the result

which refers to a function named newtraphlab5 .

You have

function [root,iter,ea] = newtraph(func,dfunc,xr,es,maxit)

which defines a function named newtraph .

It is an oddity of MATLAB that if the above function were the first function in a file named newtraphlab5.m then you would call it with the file name rather than the function name it is defined as being. However, if that is happening, chances are high that you have made a code mistake or a mistake in your MATLAB path.