I wrote the following function in a file named conditionals.m:
function result = conditionals(category, feature)
result=5;
end
I call this function from Octave's command line:
v=conditionals(3,4)
I get the following error:
error : A(I) : Index exceeds matrix dimension.
Whats wrong here?
The error:
error : A(I) : Index exceeds matrix dimension.
Indicates that octave thinks that conditionals is a matrix, not a function.
Octave probably doesn't know that conditionals is a function - and instead it's treating it as a matrix.
Have you checked to see if the function is in Octave's search path?
This works for me.
octave> function result = conditionals (category, feature)
> result = 5;
> endfunction
octave> v = conditionals (3, 4)
v = 5
The error suggests that you have a variable with the same name as the function. Type whos at the Octave prompt to see a list of defined variables. If you see one named conditionals, remove it with clear conditionals
Also, if conditionals is a conditionals.m file, make sure it's on the function search path. Run path at the Octave prompt to see the function search path. Run which conditionals at the command prompt to see where the function is located.
It happened to me as well and it can happen on any command, regardless of the command name. When I run the PS1(">>"); to change the command prompt in Ovtave, I got the same error.
octave-3.2.3.exe:9> PS1(">>");
error: A(I): Index exceeds matrix dimension.
As others also mentioned, this error fires when there is a parameter with the same command name. It happens when we mistakenly enter the command with wrong syntax and hence, octave run the command and produce a variable with your command name that overload the internal command.
You can verify this status by who command. If you can see the same variable name as your command here, you have to remove it. Use clear variable_name to remove the variable.
Here is my output for PS1 command.
Hope it helps.
Related
I am trying out a project https://github.com/janstenum/GaitAnalysis-PoseEstimation and when I run the command correctLegID_openpose.m as said in the documentation, I get this error
Not enough input arguments.
Error in correctLegID_openpose (line 3)
file = sprintf('%s%s',output_name,'_openpose.mat');
Error in run (line 91)
evalin('caller', strcat(script, ';'));
I tried running the command normally by using
run("correctLegID_openpose.m")
run() is for scripts, not for functions that take arguments. If correctLegID_openpose.m is on your Matlab search path, you can just call it directly and supply the missing input argument:
output_name = 'filename';
correctLegID_openpose(output_name)
If I write this:
clc
clear
close all
format long
fprintf( 1, 'Starting...\n' )
function results = do_thing()
results = 1;
end
results = do_thing()
And run it with Octave, it works correctly:
Starting...
results = 1
But if I try to run it with Matlab 2017b, it throws this error:
Error: File: testfile.m Line: 13 Column: 1
Function definitions in a script must appear at the end of the file.
Move all statements after the "do_thing" function definition to before the first local function
definition.
Then, if I fix the error as follows:
clc
clear
close all
format long
fprintf( 1, 'Starting...\n' )
results = do_thing()
function results = do_thing()
results = 1;
end
It works correctly on Matlab:
Starting...
results =
1
But now, it stopped working with Octave:
Starting...
error: 'do_thing' undefined near line 8 column 11
error: called from
testfile at line 8 column 9
This problem was explained on this question: Run octave script file containing a function definition
How to fix it without having to create a separate and exclusive file for the function do_thing()?
Is this issue fixed on some newer version of Matlab as 2019a?
The answer is in the comments, but for the sake of clarity:
% in file `do_thing.m`
function results = do_thing()
results = 1;
end
% in your script file
clc; clear; close all; format long;
fprintf( 1, 'Starting...\n' );
results = do_thing();
Accompanying explanatory rant:
The canonical and safest way to define functions is to define them in their own file, and make this file accessible in octave / matlab's path.
Octave has supported 'dynamic' function definitions (i.e. in the context of a script or the command-line) since practically forever. However, for the purposes of compatibility, since matlab did not support this, most people did not use it, and quite sensibly relied on the canonical way instead.
Matlab has recently finally introduced dynamic function definitions too, but has opted to implement them explicitly in a way that breaks compatibility with octave, as you describe above. (rant: this may be a coincidence and an earnest design decision, but I do note that it also happens to go against prior matlab conventions regarding nested functions, which were allowed to be defined anywhere within their enclosing scope).
In a sense, nothing has changed. Matlab was incompatible with advanced octave functionality, and now that it has introduced its own implementation of this functionality, it is still incompatible. This is a blessing in disguise. Why? Because, if you want intercompatible code, you should rely on the canonical form and good programming practices instead of littering your scripts with dynamic functions, which is what you should be doing anyway.
Octave's implementation of local functions in scripts is different from Matlab's. Octave requires that local functions in scripts be defined before their use. But Matlab requires that local functions in scripts all be defined at the end of the file.
So you can use local functions in scripts on both applications, but you can't write a script that will work on both. So just use functions if you want code that will work on both Matlab and Octave.
Examples:
Functions at end
disp('Hello world')
foo(42);
function foo(x)
disp(x);
end
In Matlab R2019a:
>> myscript
Hello world
42
In Octave 5.1.0:
octave:1> myscript
Hello world
error: 'foo' undefined near line 2 column 1
error: called from
myscript at line 2 column 1
Functions before use
disp('Hello world')
function foo(x)
disp(x);
end
foo(42);
In Matlab R2019a:
>> myscript
Error: File: myscript.m Line: 7 Column: 1
Function definitions in a script must appear at the end of the file.
Move all statements after the "foo" function definition to before the first local function definition.
In Octave 5.1.0:
octave:2> myscript
Hello world
42
How it works
Note that technically the functions here in Octave are not "local functions", but "command-line functions". Instead of defining a function that is local to the script, they define global functions that come into existence when the function statement is evaluated.
The following code works on both Matlab and Octave:
if exist('do_nothing') == 0
disp('function not yet defined, run script again')
else
do_nothing
end
%====
function results = do_nothing()
results = 1;
end
When run on octave, the first attempt exits with the message, but subsequent attempts succeed. On Matlab, it works the first time. While this works on both platforms, it is less than ideal, since it requires that much of the script code be placed inside an "if" statement block.
I'm new to MATLAB, and I have the following problem:
I have the line:
[~, j] = min(matrix);
I don't understand what the ~ sign is for(I have to learn this code..) and the error is:
Expression or statement is incorrect--possibly unbalanced (, {, or [.
What can be the reason?
Another question, suppose I have got a file.m and inside of it I have the declaration:
methods (Static)
function var = func(n, d)
How do I call this function with the 2 parameters from the command windows?
i dont understand whats for ~ sign
Discard first returning output, it is not going to be used.
What can be the reason?
What version of Matlab do you use? This syntax has only been part of MATLAB since about R2009b or so.
How do i call this function func with the 2 parameters from the command windows?
Yes, otherwise - http://www.mathworks.com/help/matlab/matlab_prog/support-variable-number-of-inputs.html
I have the following call to a function:
callfun(I1, I2, [X Y ones(n,1)], w, m)
But, I'm getting:
Error: File: callfun.m Line: 20 Column: 3
Unexpected MATLAB expression.
Why is that?
Thanks.
The error says, that your function callfun has a syntax error in line 20. Probably some character which is not allowed.
It can be also a problem of duplicated function definition. A function inside callfun.m may have the same name as a built-in MATLAB function, what yields an error.
From http://www.mathworks.com/matlabcentral/answers/214993-how-to-solve-error-unexpected-matlab-expression-workspacefunc-287:
Do you have any user-defined functions called builtin, strjoin, or strsplit? MATLAB has these defined internally, and having any outside functions that shadow these built-in ones would result in this error. If you are unsure if you have created such functions, typing the command:
>>which functionName -all
will show you the path to all items on the MATLAB path with the name "functionName"
I have created a function in MATLAB & have saved it as an m file. When I run my function, it's fine. However using the Windows 7 scheduler it goes to run my function and gives the error message 'Undefined variable 'myMethod' or function 'myMethod.m'.
When I run the which('myMethod.m') it returns the correct folder so not sure what this error message is about?
The pwd method returns the correct address of where my function is too, C:\SomeFolder\MATLAB\Me
Probably its simply not finding the function because it is not on the path.
Assuming you can run builtin functions via the scheduler, try something like this:
p = path
save p
% save c:\ p
In case you cannot even find the saved file, use the last line instead.
Match the path with your files location and presumably the path does not contain the folder which holds your file.