I'm new to Matlab and SIMULINK, and I know that this might be easy. But I just can't find the answer on the internet.
I'm building a SIMULINK model (group of blocks) and I want to set the values inside the blocks as variables so I can maybe control it from an m file or something. How can I do this?
As #rayryeng has pointed out you can just type the name of a variable in place of the parameter value of blocks, and then whatever value that variable is set to in your Matlab workspace will be used.
Whenever I do this, I like to set default values of the variables in the models intialization callback function details here. That way your model is portable and will run on it's own.
In the simulink model,
In the 'Value' field of a Constant Block, enter the variable name. The constant block will then look like this: (see uplim and lowlim)
Now, whenever you wish to change the variable's value, execute the following commands through an m-file:
Let's assume the variable's name is pressure and the new value is 5.
assignin('base','pressure',5);
set_param('path of constant block','Value','pressure');
The path to a constant block (or any simulink block) looks something like this: modelname/Constant2 (considering it is the top level of your model; Constant Block number can vary)
Related
I want to define a few variables in a simulink model. The matlab function block doesn't work because the variables are local. The variables are not input to other blocks, but instead, the variables are parameters to other blocks.
Basically, I want to have a block where I can define a bunch of variables that set the parameters for other blocks. I did this once in the past more than a few years ago now, but I can't find or remember how to do it.
I thought I used a block, but potentially, I set the variables somewhere in model settings or something. I can't remember, and I am not having luck finding it. Any help is much appreciated! I feel this is simple, but I just can't find the solution.
You can do this by defining your data in the model's "Model Workspace", like this:
. There's more about the Model Workspace in the doc. There are various options as to where you can store the parameters.
You can use Simulink data dictionary or model workspace to store the variables/Parameters. go through this link to get more info Usage of the variables/Parameters/Signals for simulink models
In the simulation window, before the run, I'd like to change some probability distributions (e.g. delay time) by typing, for example, "triangular(5, 20, 15)" into a specific editbox linked to a variable.
I know how to do this with static values, but I couldn't figure out how to do the same with probability distributions.
AnyLogic offers a built-in functionality for that with com.anylogic.engine.database.CodeValue.
It is originally meant that a distribution function stored as text in the internal database can be parsed to java code and executed, but it actually also works without the database and for any kind of code. It is the same idea as in Benjamin's answer, just that you do not need to add any external java library.
Use it like this:
CodeValue myCode = new CodeValue(this,"....java code to be executed");
myCode.execute();
And in your specific case, assuming you have a variable named variableA and an editbox named editbox, use the following to evaluate the expression, get a value and set it for the variable:
CodeValue myCode = new CodeValue(this,"variableA = "+editbox.getText());
myCode.execute();
Obviously, allowing the user to type any command there and running it without a check or error treatment is a bad idea, be aware of that.
This is a Java issue. You need to convert a String (your editbox content) to executable code. Not straight-forward but also not impossible, see Convert String to Code and similar posts.
I am using functions from a MATLAB package ("EEGLAB"). One of the functions I'm using ("pop_selectcomp") creates a GUI. However, when I try to interact with the GUI, an error results: an expected variable (In this case "EEG", a data structure) is not defined. That's odd, because pop_selectcomp has EEG as an input. I discovered that declaring global EEG anywhere in the function stack above my call to pop_selectcomp makes EEG available to it again. This is the structure of my function stack.
Main Script
data import function loads variable "EEG"
function to process data
function call to pop_selectcomp
So declaring EEG as a global in the main script or the data processing function fixes the problem.
My interpretation is that when pop_selectcomp creates its GUI window, it's being created outside of my function stack in the main workspace or something like that. So, the EEG variable is only available to it if it's been declared global above the function call. I'm not very familiar with Matlab figures and GUIs, but I guess that normally pop_selectcomps doesn't have this problem because it's not called as a sub-function.
Is there any better way to make this work? Can I somehow point pop_selectcomps' GUI at the correct sub-workspace where it will find the variables it needs? I can modify pop_selectcomps if I have to, although that would be messier. The function can be found here:
https://sccn.ucsd.edu/svn/software/eeglab/functions/popfunc/pop_selectcomps.m
I have a problem. I have an embedded function in my simulink model which has a structure (struct) as parameter. It contains only numerical values and I generate an S-Function of the embedded function by right clicking on the block and C/C++ code --> Generate S-function.
I then have the compiled block, if I try to change some values of my struct nothing changes (the fields of my struct stay the same as when I first compiled my embedded function).
When I compiled the embedded function block I selected the parameter to be tunable. I selected the parameter to be tunable in the Model Explorer. I tried to follow this video tutorial by mathworks: http://fr.mathworks.com/videos/tunable-structure-parameters-68947.html (The video is for r2010a while I am at r2015b) It is a bit different the interface in r2015b (from the one in the video) but when I click on Configure , like the guy does in the video, nothing happens.
Could you help me please?
Thanks a lot.
Once I had also decided to reduce the number of tunable parameters by checking the 'inline parameters' checkbox and then specifying the exception variables (variable that have the permission to be tunable even when 'inline parameters' is turned on. It did not work.
In case you aim does not heavily rely on optimization, it would be better if you simply turn off 'inline parameters'.
After that, the constant blocks (i suppose you are giving the input to your s-function from constant blocks) will become tunable.
Another advice: add mex in the init function of your model callbacks. It will save you from getting weird output (usually due to uncleared/un-reset variables from previous runs).
Hope it helps!
I have built a matlab function and I want to access one of its variables ,say x in the workspace. If I write x in the workspace it says Undefined function or variable "x"
Using the global modifier will definitely make your variable visible to the workspace, but it will also make it visible to any other function you call that happens to use that variable name. So if you insist on doing it this way, make sure that your variable name is unique.
A better way, in my opinion, is to pass back the value of the variable as a return value from the function, though this may require changes to calling functions.
Other options are detailed here:
http://www.mathworks.com/help/matlab/matlab_prog/share-data-between-workspaces.html