I have a variable ( cell array) created in base workspace in matlab..i am building an app in appdesigner to access the base workspace variable and find the transpose at push of a button.
when i tried to use the variable in callbackfunction i get the error :
undefined function or variable even though the variable defined in base workspace.
Kindly help me with a solution.
I literally just got Matlab 2016 yesterday, and I haven't tried what you're attempting, but I'm guessing it's similar to similar scenarios in functions. So I guess you can try this:
localVariableInCallback = evalin('base','nameOfVariableInWorkspace');
Where
localVariableInCallback is a local variable in the callback function
nameOfVariableInWorkspace is the variable in your base workspace
Reference: Matlab 'evalin' documentation: https://uk.mathworks.com/help/matlab/ref/evalin.html
I noticed you posted same question twice, and was downvoted. I strongly recommend that you have a look at what they suggested and provide a Minimal, Complete, and Verifiable example for your questions.
Related
A question that pops up quite frequently in different shapes and sizes is: Why do I get the following error message:
"Undefined function 'function_name' for input arguments of type 'double'."
This post attempts to address all the different scenarios where this error message can occur, and propose solutions for how it can be resolved.
If you stumble upon this error message and don't know what it means. Take comfort in this: 90% of us have googled the same phrase.
"Undefined function 'int' for input arguments of type 'double'."
The error message is pretty self-explanatory but may still cause confusion. (I chose 'int' at random, it could just as well be 'train', 'table', 'my_function' or anything else).
There are two main cases where this error occurs:
You are trying to use a function that doesn't exist (yet)
You are trying to access an element in a variable that doesn't exist (yet)
What do you do if you get this error?
First, you might want to try which. This will tell you whether or not the function or variable you're trying to use is defined.
which int
'int' not found.
It's quite obvious, that Matlab can't find any functions or variables named int. Trying to use it is therefore futile. Let's compare it to max:
which max
built-in (C:\Program Files\MATLAB\R2014b\toolbox\matlab\datafun\#logical\max) % logical method
But, you might get the following, even if you get the "Undefined function 'x' ...". If so, see point 3 below.
which x
x is a variable.
1. But the function "int" exists! It is even documented here!?
Yes, int exists, but only if you have the Symbolic Toolbox. Since Toolboxes are additional packages that must be purchased separately (and can be quite expensive), chances are you don't have that package.
If you get the "Undefined function" error, but find the function in the documentation, have a look in the menu to the left, or simply check the address. Standard Matlab functions have addresses such as:
mathworks.com/help/matlab/ref/max.html
^^^^^^
Notice the "matlab" part. If you see this, then you are using a function that is part of the core Matlab.
If however, you see an address such as the one below, then the function you are trying to use is part of the Symbolic Toolbox:
mathworks.com/help/symbolic/int.html
^^^^^^^^
or maybe it's part of the Neural Network Toolbox:
mathworks.com/help/nnet/ref/train.html
^^^^
Solution: Find another function that isn't part of a toolbox you don't have. Chances are you'll find what you are looking for if you are a skilled googler. If you can't find it, ask for help. Explain what you have tried, and show that you have done some effort!
2. But the function is documented here, and is part of core Matlab!?
Even though a function is part of the standard Matlab installation, and is well documented, you may still get this error. The most likely cause for this error is that you are using an older version of Matlab. If you check the documentation you'll see the following at the bottom of the page:
Introduced in R2013b
So, if you are using R2012b then you can't use for instance table.
Solution: Check if the function is defined in your version of Matlab. If it's not yet implemented then you either need to update Matlab or find another way to do it. An alternative to table can for instance be to use cells or structs.
3. But the variable "my_variable" exists! I created it in the line above!
No, you didn't. Chances are you created the variable myvariable, my_Variable, my_Variable or something similar in the line above. It's also possible that you have created it, but have accidentally cleared it.
Solution: Go through the code. Look for typos, places where you have accidentally cleared the variable etc. Inside the Matlab editor you will get the following line at the bottom if you mark a variable: "3 usages of "x" found" if you have defined and used the function. You will also get an orange line underneath unused variables.
4. But I get "y is a variable" when I type which y?
If you get the error above "Undefined function 'y', but which tells you y exists, your error message contains a few more lines:
my_function(x)
Undefined function or variable 'y'.
Error in my_function (line 2)
t = x*y;
>> which y
y is a variable.
What this tells you is that you have a variable called y in your Matlab Workspace (also check this link).
The problem is that functions can't access this workspace:
Functions do not use the base workspace. Every function has its own function workspace.
If you want a function to see and use a variable, you must pass it as an argument. This way the variable will be part of the local workspace for that function. Similarly, if you want variables created inside the function to be accessible outside of the function you must have them as output from the function.
Solution: Pass the variables you want to use as input arguments to the function you use. Make sure the names inside the functions are internally consistent. I.e. it must have the same name throughout the function. Note that there is no connection between the variable names outside and inside the function.
5. But I pass the variable as an input to the function, but I still get the same error message!?
Yes, you probably use the variable as input. However, the variable names are not necessarily the same in different functions (most often they are not).
Suppose you have the function:
function output = my_function(x)
output = 2*y;
end
You'll get the same error as above if you call it from the workspace as in the code below, even though you are using y as input variable, and use y inside the function.
y = 3;
res = my_function(y)
This is because, inside the function my_function, the variable you use as input will be called x, regardless of what it was called outside the function.
Solution: Change the name of the input variable name in the function header, or change the name of the variable throughout the function.
6. But I have created x as a global variable!?
First off: Chances are, if you're reading this post, then you are better off passing variables as arguments rather than using global variables.
It's not enough to declare a variable as global in the Matlab workspace. It must be declared in every function you use it in. So, if you have a global variable x, you need to do global x in every function.
Solution: Rewrite your code and pass variables as arguments instead of using global variables. If this is not an option, add global x in all functions where you're using it.
In addition to this answer, you can refer to the official Matlab FAQ.
I also got
Undefined function '...' for input arguments of type 'double'.
error and I tried the recommendations mentioned above but they could not solve my problem. Then, I realized that there is a special character (*) in my current working directory so I solve the problem when I changed the name of the directory.
Lastly, do not forget to change the current directory after the change operation by using cd argument.
Another way of looking at the problem:
the input arguments should be in an order such that the explanation of the function can read it.
A question that pops up quite frequently in different shapes and sizes is: Why do I get the following error message:
"Undefined function 'function_name' for input arguments of type 'double'."
This post attempts to address all the different scenarios where this error message can occur, and propose solutions for how it can be resolved.
If you stumble upon this error message and don't know what it means. Take comfort in this: 90% of us have googled the same phrase.
"Undefined function 'int' for input arguments of type 'double'."
The error message is pretty self-explanatory but may still cause confusion. (I chose 'int' at random, it could just as well be 'train', 'table', 'my_function' or anything else).
There are two main cases where this error occurs:
You are trying to use a function that doesn't exist (yet)
You are trying to access an element in a variable that doesn't exist (yet)
What do you do if you get this error?
First, you might want to try which. This will tell you whether or not the function or variable you're trying to use is defined.
which int
'int' not found.
It's quite obvious, that Matlab can't find any functions or variables named int. Trying to use it is therefore futile. Let's compare it to max:
which max
built-in (C:\Program Files\MATLAB\R2014b\toolbox\matlab\datafun\#logical\max) % logical method
But, you might get the following, even if you get the "Undefined function 'x' ...". If so, see point 3 below.
which x
x is a variable.
1. But the function "int" exists! It is even documented here!?
Yes, int exists, but only if you have the Symbolic Toolbox. Since Toolboxes are additional packages that must be purchased separately (and can be quite expensive), chances are you don't have that package.
If you get the "Undefined function" error, but find the function in the documentation, have a look in the menu to the left, or simply check the address. Standard Matlab functions have addresses such as:
mathworks.com/help/matlab/ref/max.html
^^^^^^
Notice the "matlab" part. If you see this, then you are using a function that is part of the core Matlab.
If however, you see an address such as the one below, then the function you are trying to use is part of the Symbolic Toolbox:
mathworks.com/help/symbolic/int.html
^^^^^^^^
or maybe it's part of the Neural Network Toolbox:
mathworks.com/help/nnet/ref/train.html
^^^^
Solution: Find another function that isn't part of a toolbox you don't have. Chances are you'll find what you are looking for if you are a skilled googler. If you can't find it, ask for help. Explain what you have tried, and show that you have done some effort!
2. But the function is documented here, and is part of core Matlab!?
Even though a function is part of the standard Matlab installation, and is well documented, you may still get this error. The most likely cause for this error is that you are using an older version of Matlab. If you check the documentation you'll see the following at the bottom of the page:
Introduced in R2013b
So, if you are using R2012b then you can't use for instance table.
Solution: Check if the function is defined in your version of Matlab. If it's not yet implemented then you either need to update Matlab or find another way to do it. An alternative to table can for instance be to use cells or structs.
3. But the variable "my_variable" exists! I created it in the line above!
No, you didn't. Chances are you created the variable myvariable, my_Variable, my_Variable or something similar in the line above. It's also possible that you have created it, but have accidentally cleared it.
Solution: Go through the code. Look for typos, places where you have accidentally cleared the variable etc. Inside the Matlab editor you will get the following line at the bottom if you mark a variable: "3 usages of "x" found" if you have defined and used the function. You will also get an orange line underneath unused variables.
4. But I get "y is a variable" when I type which y?
If you get the error above "Undefined function 'y', but which tells you y exists, your error message contains a few more lines:
my_function(x)
Undefined function or variable 'y'.
Error in my_function (line 2)
t = x*y;
>> which y
y is a variable.
What this tells you is that you have a variable called y in your Matlab Workspace (also check this link).
The problem is that functions can't access this workspace:
Functions do not use the base workspace. Every function has its own function workspace.
If you want a function to see and use a variable, you must pass it as an argument. This way the variable will be part of the local workspace for that function. Similarly, if you want variables created inside the function to be accessible outside of the function you must have them as output from the function.
Solution: Pass the variables you want to use as input arguments to the function you use. Make sure the names inside the functions are internally consistent. I.e. it must have the same name throughout the function. Note that there is no connection between the variable names outside and inside the function.
5. But I pass the variable as an input to the function, but I still get the same error message!?
Yes, you probably use the variable as input. However, the variable names are not necessarily the same in different functions (most often they are not).
Suppose you have the function:
function output = my_function(x)
output = 2*y;
end
You'll get the same error as above if you call it from the workspace as in the code below, even though you are using y as input variable, and use y inside the function.
y = 3;
res = my_function(y)
This is because, inside the function my_function, the variable you use as input will be called x, regardless of what it was called outside the function.
Solution: Change the name of the input variable name in the function header, or change the name of the variable throughout the function.
6. But I have created x as a global variable!?
First off: Chances are, if you're reading this post, then you are better off passing variables as arguments rather than using global variables.
It's not enough to declare a variable as global in the Matlab workspace. It must be declared in every function you use it in. So, if you have a global variable x, you need to do global x in every function.
Solution: Rewrite your code and pass variables as arguments instead of using global variables. If this is not an option, add global x in all functions where you're using it.
In addition to this answer, you can refer to the official Matlab FAQ.
I also got
Undefined function '...' for input arguments of type 'double'.
error and I tried the recommendations mentioned above but they could not solve my problem. Then, I realized that there is a special character (*) in my current working directory so I solve the problem when I changed the name of the directory.
Lastly, do not forget to change the current directory after the change operation by using cd argument.
Another way of looking at the problem:
the input arguments should be in an order such that the explanation of the function can read it.
I am now using Matlab GUI and have problem during accessing return values from a function which is set by set().
Situation:
I set the windowMotionFcn as below:
set(gcf,'WindowButtonMotionFcn',#test);
Function 'test' can return 2 variables (named as var1 and var2).But I dont know how to store them...
I have searched in the Internet and could not find any way.
How should I write?
Thank you for your help and kind attention.
I think that what you want to do is to return a value from the callback function. And regarding returning a value from a callback I am not sure that is possible. I found an old article from matlab newsreader. I think your problem could be similar.
However, if you have a matlab GUIDE GUI, there is a way to return a value from a gui. It is described in a matlab tutorial in matlab central: advanced-getting-an-output-from-a-guide-gui. What you must do is to modify your CloseRequestFcn and your OutputFcn.
Another way, which should work is using global variables. A global varable exist in the global workspace. That means that it can be seen and accessed by every function in matlab. Global variables are in most cases not recommended, but if no other solution exists they may be necessary. Just make sure to document them, so that the next person to take over your code knows that they are there. Also make sure to select a good name for the globals, like gblMyVar so there can be no confusion that the variable is global.
A question that pops up quite frequently in different shapes and sizes is: Why do I get the following error message:
"Undefined function 'function_name' for input arguments of type 'double'."
This post attempts to address all the different scenarios where this error message can occur, and propose solutions for how it can be resolved.
If you stumble upon this error message and don't know what it means. Take comfort in this: 90% of us have googled the same phrase.
"Undefined function 'int' for input arguments of type 'double'."
The error message is pretty self-explanatory but may still cause confusion. (I chose 'int' at random, it could just as well be 'train', 'table', 'my_function' or anything else).
There are two main cases where this error occurs:
You are trying to use a function that doesn't exist (yet)
You are trying to access an element in a variable that doesn't exist (yet)
What do you do if you get this error?
First, you might want to try which. This will tell you whether or not the function or variable you're trying to use is defined.
which int
'int' not found.
It's quite obvious, that Matlab can't find any functions or variables named int. Trying to use it is therefore futile. Let's compare it to max:
which max
built-in (C:\Program Files\MATLAB\R2014b\toolbox\matlab\datafun\#logical\max) % logical method
But, you might get the following, even if you get the "Undefined function 'x' ...". If so, see point 3 below.
which x
x is a variable.
1. But the function "int" exists! It is even documented here!?
Yes, int exists, but only if you have the Symbolic Toolbox. Since Toolboxes are additional packages that must be purchased separately (and can be quite expensive), chances are you don't have that package.
If you get the "Undefined function" error, but find the function in the documentation, have a look in the menu to the left, or simply check the address. Standard Matlab functions have addresses such as:
mathworks.com/help/matlab/ref/max.html
^^^^^^
Notice the "matlab" part. If you see this, then you are using a function that is part of the core Matlab.
If however, you see an address such as the one below, then the function you are trying to use is part of the Symbolic Toolbox:
mathworks.com/help/symbolic/int.html
^^^^^^^^
or maybe it's part of the Neural Network Toolbox:
mathworks.com/help/nnet/ref/train.html
^^^^
Solution: Find another function that isn't part of a toolbox you don't have. Chances are you'll find what you are looking for if you are a skilled googler. If you can't find it, ask for help. Explain what you have tried, and show that you have done some effort!
2. But the function is documented here, and is part of core Matlab!?
Even though a function is part of the standard Matlab installation, and is well documented, you may still get this error. The most likely cause for this error is that you are using an older version of Matlab. If you check the documentation you'll see the following at the bottom of the page:
Introduced in R2013b
So, if you are using R2012b then you can't use for instance table.
Solution: Check if the function is defined in your version of Matlab. If it's not yet implemented then you either need to update Matlab or find another way to do it. An alternative to table can for instance be to use cells or structs.
3. But the variable "my_variable" exists! I created it in the line above!
No, you didn't. Chances are you created the variable myvariable, my_Variable, my_Variable or something similar in the line above. It's also possible that you have created it, but have accidentally cleared it.
Solution: Go through the code. Look for typos, places where you have accidentally cleared the variable etc. Inside the Matlab editor you will get the following line at the bottom if you mark a variable: "3 usages of "x" found" if you have defined and used the function. You will also get an orange line underneath unused variables.
4. But I get "y is a variable" when I type which y?
If you get the error above "Undefined function 'y', but which tells you y exists, your error message contains a few more lines:
my_function(x)
Undefined function or variable 'y'.
Error in my_function (line 2)
t = x*y;
>> which y
y is a variable.
What this tells you is that you have a variable called y in your Matlab Workspace (also check this link).
The problem is that functions can't access this workspace:
Functions do not use the base workspace. Every function has its own function workspace.
If you want a function to see and use a variable, you must pass it as an argument. This way the variable will be part of the local workspace for that function. Similarly, if you want variables created inside the function to be accessible outside of the function you must have them as output from the function.
Solution: Pass the variables you want to use as input arguments to the function you use. Make sure the names inside the functions are internally consistent. I.e. it must have the same name throughout the function. Note that there is no connection between the variable names outside and inside the function.
5. But I pass the variable as an input to the function, but I still get the same error message!?
Yes, you probably use the variable as input. However, the variable names are not necessarily the same in different functions (most often they are not).
Suppose you have the function:
function output = my_function(x)
output = 2*y;
end
You'll get the same error as above if you call it from the workspace as in the code below, even though you are using y as input variable, and use y inside the function.
y = 3;
res = my_function(y)
This is because, inside the function my_function, the variable you use as input will be called x, regardless of what it was called outside the function.
Solution: Change the name of the input variable name in the function header, or change the name of the variable throughout the function.
6. But I have created x as a global variable!?
First off: Chances are, if you're reading this post, then you are better off passing variables as arguments rather than using global variables.
It's not enough to declare a variable as global in the Matlab workspace. It must be declared in every function you use it in. So, if you have a global variable x, you need to do global x in every function.
Solution: Rewrite your code and pass variables as arguments instead of using global variables. If this is not an option, add global x in all functions where you're using it.
In addition to this answer, you can refer to the official Matlab FAQ.
I also got
Undefined function '...' for input arguments of type 'double'.
error and I tried the recommendations mentioned above but they could not solve my problem. Then, I realized that there is a special character (*) in my current working directory so I solve the problem when I changed the name of the directory.
Lastly, do not forget to change the current directory after the change operation by using cd argument.
Another way of looking at the problem:
the input arguments should be in an order such that the explanation of the function can read it.
i want to change function variable at each step in a for loop in matlab.
i take these steps:
i created my mfile function
function [jfun,fun]=air(x,vt,ty,tz,p2,y0)
jfun=[(cos(tz)*cos(ty)*vt/9.81)*(1-exp(-9.81*x(2)/vt)),...
x(1)*cos(tz)*cos(ty)*exp(-9.81*x(1)/vt);
(-vt*sin(tz)*cos(ty)/9.81)*exp(-9.81*x(1)/vt),...
(x(1)*sin(tz)*cos(ty)*+vt)*exp(-9.81*x(1)/vt)];
fun=[(x(1)*cos(ty)*cos(tz)*vt/9.81)*(1-exp(-9.81*x(2)/vt))-p2;...
(vt/9.81)*(x(1)*sin(tz)*cos(ty)+vt)*(1-exp(-9.81*x(2)/vt))-vt*x(2)+y0];
end
and then i used newtonSys command:
ty=rad(-23)
tz=rad(15)
p2=1.8
vt=8.4925
y0=0.2
myfun=#(x)air(x,vt,ty,tz,p2,y0)
x=newtonSys(myfun,[15 5],0.000001,0.000001,500,1)
and matlab answer:
Error in ==> Untitled18 at 7
x=newtonSys(myfun,[15 5],0.000001,0.000001,500,1)
i guess that its because of wrong use of function handle and for my function i have to use another command or i have to use another method for solving 2nonlinear equation.
First, you haven't displayed the entire error. MATLAB should tell you what the actual error is, so unless you tell us that, we won't know what's wrong.
Secondly I don't see newtonSys in my system, or in the online MATLAB documentation. So most likely it is an external program, which most people here might not be familiar with. The closest I found from a quick Google search was this, which is an implementation of Newton's method for approximating the root of a non-linear system of n-equations. Are you using the same file? If so, if you look at the comments, it says that you need to pass the function as a string. So you'd have to pass myfun as 'myfun'.
If not, could you edit your question and add the contents of the function that you're using? Without these, it's near impossible to answer your question.