Please help! "Error: Function definitions are not permitted in this context. "

Hello! I'm extremely new to Matlab, and I'm working on a homework problem, and I keep coming up with an error... I've written my functions, and defined some variables to be plugged into them. I can't even call my functions, because I get the error for writing them.

This all has to be in one m-file so I cannot save the functions in different ones... I'm not sure what to do :(

function [x,y,vx,vy] = trajectory(t,v0,th0,h0,g)      

x = v0 .* cos(th0) .* t;
y = h0 + (v0 .* sin(th0) .* t) - ((1./2) .* g .* (t.^2));
vx = v0 .* cos(th0);
vy = (v0 .* sin(th0)) - (g .* t);

function y = height(t,v0,th0,h0,g)

[x,y,vx,vy] = trajectory(t,v0,th0,h0,g);  

%(b)
v0 = 20;
th0 = 45;
h0 = 5;
g = 9.81;
t = linspace(1,4,400);

y = height(t,v0,th0,h0,g)

[Mamoona Yousaf]

Function definitions are not permitted in this context. plz tell me the meaning of this error

[Image Analyst]

Essentially, the code simplifies down to this:

function a = trajectory
a=10

function height
b = trajectory
c = height

There is nothing wrong with having that all in the same m-file. You can run it and won't get the error. Basically it runs trajectory, which never calls height at all. If it did, then since height calls trajectory, you could get an infinite loop because it would never stop.

What they probably did (but did not show) was to define t,v0,th0,h0,g in the same m-file, and this turned the two-function file (which is allowed) into a script+(2 functions) file which is not allowed. You can't start out an m-file with a script (like defining input arguments) and then follow up with function definitions. You can have a script only, or multiple functions, but not both in the same m-file.

[Walter Roberson]

Image Analyst: scripts can now have functions in them, as of R2016b.

Answer 1

[Fangjun Jiang]

In MATLAB, there are two types of code files, scripts and functions. If the first executable line of your code file is a function definition like you have in the code above, then your file is a function.

If there is other MATLAB code such as variable declarations above the first function definition, then your file is a script. It sounds like you might have additional code above the code for the two functions you gave, making the file a script.

In MATLAB versions R2016a and before, you cannot have function definitions inside a script. That is what the error message is saying. To fix the problem, save each function definition in separate files, and either create a script with the additional code or simply run the additional code in the command window before calling your functions.

In MATLAB version R2016b and after, you can have function definitions in a script, and you would not see the "Error: Function definitions are not permitted in this context" error in your case. For more information about functions in scripts, see:

https://www.mathworks.com/help/matlab/matlab_prog/local-functions-in-scripts.html.

For more information about the difference between scripts and functions, see:

https://www.mathworks.com/help/matlab/matlab_prog/scripts-and-functions.html.

[Jan]

It becomes an evergreen and should be included in the FAQ.

[binh]

thanks for your answer! I split this function to another .m file and it worked!

[Zeynab Mousavikhamene]

I have matlab 2018 and I get this error as well! Any solution?

[Walter Roberson]

Zeynab, are you storing the code into files, or are you trying to execute the function line at a command prompt?

[Lin Bo Yang]

2018 too and final how to solution it

[Walter Roberson]

You cannot execute the function operator at the command line: you have to store function code in a file.

In R2016b and later, it is permitted to have function at the end of a script file.

In R2016a and earlier, functions are not permitted in script file.

[Sihai]

Thanks for your answer, useful!

[Gabriela Diaz]

What about if we are using Matlab Online R2019b?

[Walter Roberson]

In r2019b it is still not permitted to define functions at the MATLAB command line, and it is still permitted to define functions inside a script (since R2016b).

When a function is defined inside a script, the name of the function must be different than the name of the script file.

[Arslan Nazir]

Thanks @Fangjun Jiang . Problem solved

[chorare chorare]

hello me to I also have the same problem and I know what to do

function y = pvMeasurementFcn(x,varargin)

% Extract data from inputs
Ts  = varargin{1};   
Is  = varargin{2};   
Rs = varargin{3};  
Rp = varargin{4};
vt = varargin{5};
n = varargin{6};
Voc = varargin{7};
Iph = varargin{8};

% Output equation
y = [...
    Iph-Is*exp((Voc+x(2)*Rs)/(n*vt)-1)-(Voc+x(2)*Rs/Rp); ...
    Voc];
end
>> pvMeasurementFcn
Index exceeds matrix dimensions.

Error in pvMeasurementFcn (line 4)
Ts  = varargin{1};
 

[Walter Roberson]

@chorare chorare

That function needs to be passed a minimum of 9 parameters. The first one is x, then Ts, Is, Rs, and through Rp, vt, n, Voc, and Iph .

You attempted to run the function without passing any parameters at all. The function has no idea where to get the values for Ts, Is, Rs and so on from.

You cannot just press the green Run button to invoke that function. You need to go down to the command window and invoke it passing in values, like

y = pVMeasurements(x20210903, Ts7, Is7, Rs7, Rp5, vt4, 17, Voc_holiday, pale_ale)

but using the actual variable names for your data instead of the names I gave here.

Answer 2

[Walter Roberson]

In addition to what Fangjun wrote:

When you are not already executing within a given file, MATLAB can only find the very first function in that file, and that first function name must be the same name as the file.

Therefore, the order of functions in the file should be that the very first one is the "driver" function (the one that sets up everything and calls the other functions to do the work), and the functions that do the internal work should be after that in the file.

If you look at the function order you have coded above, you have coded the internal routine first, and then coded a routine that calls that internal routine. You would, however, not be able to activate that second routine from the MATLAB command line.

So... what you need to do is take the line that start at %(b) through to the end of the file, and move those lines to the beginning of the file, and then you have to insert a "function" line at the very top, naming it appropriately for your assignment conditions. I can see from the code that those lines set things up and then call the internal routines, so those lines should be in the first function.

[marah]

Error using struct2handle

Error while evaluating uicontrol CreateFcn

function varargout = lagrange(varargin)

|

Error: Function definitions are not permitted in this context.

function varargout = lagrange(varargin)

|

Error: Function definitions are not permitted in this context.

Answer 3

[Kamil Kasic]

What is wrong here?

basic example from Matlab help:

function y = average(x)
if ~isvector(x)
    error('Input must be a vector')
end
y = sum(x)/length(x); 
end
  function y = average(x)
  |
Error: Function definitions are not permitted in this context.

[Walter Roberson]

You need to store that in a file named average.m and run it from the file. You cannot create functions at the command prompt.

[Alexandria James]

Thank you! This was much simpler to understand!

[Ahmed Saeed Mansour]

You are amazing! Thanks!

[ankar saha]

what is wrong here

clc; close all; clear all;

input_data = zeros(1,10);

y_cofficient = [1 -1 -1];

x_cofficient = [0 0];

initial_condition = [0 1];

yn_function_generated = filter(x_cofficient,y_cofficient,input_data);

yn = myFilter(x_cofficient, y_cofficient, input_data, initial_condition);

subplot(4,1,1)

% plot(input_data);

stem(input_data);

title('Input data');

grid on;

subplot(4,1,[2,3]);

% plot(yy, LineWidth=1);

stem(yn);

title('Custom calculated');

grid on;

subplot(4,1,4);

% plot(y, LineWidth=1);

stem(yn_function_generated);

title('Function generated');

grid on;

% My Function

function [y] = myFilter(xCoff, yCoff, input_data, initial_condition)

xCoff_len = length(xCoff);

yCoff_len = length(yCoff);

xCoff = [xCoff, zeros(1, length(input_data) - xCoff_len)];

yCoff = [yCoff, zeros(1, length(input_data) - yCoff_len)];

output_size = length(xCoff);

y = zeros(1, max(output_size, length(initial_condition)));

for i = 1 : length(initial_condition)

y(i) = initial_condition(i);

end

for n = length(initial_condition)+1 : length(y)

y_sum = 0;

x_sum = 0;

for j = 2 : n

y_sum = y_sum + (yCoff(j) * y(n - j + 1));

end

for j = 1 : n

x_sum = x_sum + (xCoff(j) * input_data(n - j + 1));

end

y(n) = (x_sum - y_sum)/yCoff(1);

end

end

Answer 4

[Gedion Teklewolde]

Even when it is saved in appropriate name file.m it still fails.

clc
clear
clc
%
% Newton-Raphson method
%
function [x0,err] = newraph(x0)
maxit = 100;
tol = 1.0e-6;
err = 100.0;
icount = 0;
xold =x0;
while (err > tol & icount <= maxit)
icount = icount + 1;
f = funkeval(xold);
df = dfunkeval(xold);
xnew = xold - f/df;
if (icount > 1)
err = abs((xnew - xold)/xnew);
end
fprintf(1,'icount = %i xold = %e f = %e df = %e xnew = %e err = %e \n',icount, xold, f, df, xnew, err);
xold = xnew;
end
%
x0 = xnew;
if (icount >= maxit)
% you ran out of iterations
fprintf(1,'Sorry. You did not converge in %i iterations.\n',maxit);
fprintf(1,'The final value of x was %e \n', x0);
end
function f = funkeval(x)
f = x + log(x);
function df = dfunkeval(x)
df = 1 + 1/x;

[Walter Roberson]

It is not clear what was stored in which file. The 'clc' at the top of the code is not the word 'function' or 'classdef' so whatever code is in the same file as the 'clc' is part of a "script" rather than a function file. Function files must start with "function", and functions can also be defined in "classdef" files, but functions cannot be defined in scripts.

[Walter Roberson]

functions can now be stored in scripts since r2016b

Answer 5

[Gireesha Obulaporam]

I wold like to implement a Genetic Algorithm in MATLAB. So, first I tried to execute the fitness value. I entered the function name called myFitness() which is as shown below:

                        function y = myFitness(x)
It displays me the "Error: Function definitions are not permitted in this context".
Please suggest me how to resolve it.

[Walter Roberson]

You can never use "function" at the command line.

If you are using R2016a or earlier then functions can only be defined in a file that starts with function or classdef. In R2016b you can also put functions in a script.

Answer 6

[Valeria Martinuzzi]

This function file is giving me an error even though it seems right. It is telling me that "Function definitions are not permited on this context" This is the file:

function [s,flag] = setupSerial(s)

%Initialize the serial port communication between Arduino and MATLAB
%The input value is the COMPORT should be changed as per requirement
%We ensure that the arduino is also communication with MATLAB at this
%time. A predefined code on the Arduino acknowledges this.
%If setup is complete then the value of setup is returned as 1 else 0
flag = 1;

s= serial('COM3');

set(s,'DataBits', 8);

set(s,'StopBits', 1);

set(s,'BaudRate', 9600);

set(s,'Parity','none');

fopen(s);

a='b';

while (a~='a')

      a=fread(s,1,'uchar');

end

if (a=='a')

      disp('serial read');

end

fprintf(s,'%c','a');

mbox = msgbox('Serial Communication setup.'); uiwait(mbox);

fscanf(s,'%u');

end

Help please?

[Walter Roberson]

You need to store that code in a file named setupSerial.m

Answer 7

[Nkwentie Musi]

after defining my function like this Function(Zg,Zt,Zc,Yg,ZT,YT)= LineParameters(Mu,Eo,Rsu,Geom,Ncon,Ns,w) i have this error when executing the program "??? Error: File: testfinal.m Line: 41 Column: 1 Function definitions are not permitted in this context." what was i suppose to do

[Walter Roberson]

Function(Zg,Zt,Zc,Yg,ZT,YT)= LineParameters(Mu,Eo,Rsu,Geom,Ncon,Ns,w)

is not valid syntax for defining a function. You need [] instead of () on the left hand side:

function [Zg, Zt, Zc, Yg, ZT, YT] = LineParameters(Mu, Eo, Rsu, Geom, Ncon, Ns, w)

[marah]

When I run the interface, I get this error

function varargout = lagrange(varargin)

|

Error: Function definitions are not permitted in this context.

function varargout = lagrange(varargin)

|

Error: Function definitions are not permitted in this context.

can you help me

[Walter Roberson]

marah

You are trying to define a function at the command line. You need to store the code in lagrange.m

Answer 8

[Han Wang]

There is nothing wrong creating functions in .m files, but I think the mistake you are making is that you didn't put the functions at the END of you mfile. Matlab actually enforces that they have to be placed at the end of the file, in order to avoid confusions like the one you have shown in your example. I think apparently, Matlab thinks your codes following %(b) are part of the function "height", and thus it gets confused somehow.

Matlab is indeed sending you a wrong error message because it minsinterprets your whole code structure. You can try moving your main routine following %(b) to the beginning of the code. Also, it helps to attach "end" to each function you have defined.

I have encountered similar situations like yours, where I forgot to attach an "end" to a "for" loop in the main routine, and Matlab sends me the same error message as yours, apparently confused with the code structure.

[Walter Roberson]

At the time the question was asked in 2011 functions could not be stored in script files .

[Steven Lord]

Matlab actually enforces that they have to be placed at the end of the file, in order to avoid confusions like the one you have shown in your example.

That's not completely correct. There are three scenarios in which ending each function in a file with an end statement is required. See the "End Statements" section on this documentation page for the list of those scenarios.

You can have a function file in which none of the functions end with an end or a function file in which all of the functions end with an end. What's not allowed is for some but not all of the functions to end with an end.