I have noticed that when a function is overridden the help fcn is not. I created a custom function using the same name as a built in function. Trying:
which fcn
Yields the right\function.m, but when I use the help function
help fcn
I get the help for the built in function. However, if I instead type
help fcn.m
I get the correct help. This is ambiguous and disturbing and may lead to confusion about which file is the used one. That is why I wonder: is it possible to override the help as well?.
I know that many does not recommend overriding in matlab, but there are times when it may be worth. For this occation it means that I does not need to change all legacy code where the function is used and also it is not good to have too many version of a function (mycdfplot is already taken and some may have local versions as well).
Short answer: NO.
(sorry)
To develop a bit:
If you overload your own function, you can force the help to point to a specific function by playing with the function precedence order and the order of the path. But for Matlab built-in function, they always take precedence over your custom functions.
The only way for the help to reach your custom function is how you described, by specifying .m
From Matlab (2013b) help:
Note: When multiple programs have the same name, the help command
determines which help text to display by applying the rules described
in Function Precedence
Order.
However, if a program has the same name as a MathWorks function, the
Help on Selection option in context menus always displays
documentation for the MathWorks function.
Related
I am currently working on the implementation of some C-Code in a Simulink model using the S-Function Builder block.
The code uses various timers and counters, which are defined as static variables to enable the access to the data in following simulation steps.
However, if I start the simulation MATLAB crashes without error message ('Fatal Exception'). To test I defined the variables without the 'static' statement. The Simulation works in this case, however with (logically) wrong results of the S-Function.
Has anybody else faced similar issues or knows how to declare static variables in Simulink?
P.S.
I know I could use Work Vectors, which I do not intend to do, since it would result in huge efforts in adopting the function to do so.
Furthermore I could simply build a feed-back loop in the model using a memory block. For approximately 100 variables this solution would also be pretty impractical.
Not a solution, but a possible workaround is to use the coder.ceval functionality. I have used this to wrap a C-function with similar (static variables used as counters) function. The coder.ceval call is then placed in an embedded matlab block. Possibly some definitions of the interfaces must also be made (structures / bus objects).
Check coder.ceval, coder.rref and coder.wref for the call structure.
It seems like it was a bug in Simulink or the MinGW Compiler. However I tore down the code, ending up with it crashing with the call of one specific variable. I renamed the variable, since I could not find any error in the syntax. Now everything works fine...
The variable name had various underscores and capital letters - in case anyone makes similar experiences.
I'm using some third-party package on MATLAB for data analysis. It was compiled using C#, but by default it displayed the results. I want to suppress this display, but should modify the C codes to achieve this. As I'm not familiar with C# and thus it troubles me to re-compile the modified codes, I wonder whether there is a general way to suppress the display in MATLAB as it has provided a way for each built-in function.
Edit:
#bushmills is correct. The function evalc suggested in this thread works. But it can significantly slow down the computation. Is there a better way, for example, declare warning('off',msgid) at the beginning, to suppress display in current function?
Thanks.
I'm trying to build a Mex function in Matlab-r2015a using Matlab Coder. The entry point function I want to convert is alg.m which is called by main.m.
Following the procedure, I'm at the step in which I'm asked to "define the type of each input for every entry point function". I choose the automatic procedure and enter main.m
My problem is: in order to define the type of each input, the Matlab Coder takes a very long time; the same problem appears at the next step, when I have to check whether there are issues in the Matlab code. Is that because Matlab has to execute the whole main.m+alg.m?
I suspect this should be the case because when I impose values of parameters that make the computation faster, the input types and issue checks are done immediately. Anyway, I would like to have some more explanations and, if any, suggestions to solve the problem.
You are correct, both steps Define Input Types and Check for Run-Time Issues run main.m which will in turn run alg.m.
If the input data types for the entry-point function don’t change, two test-benches (namely two versions of your main.m) can be written – a shorter one that invokes the entry-point once for defining input types, and a more comprehensive one that thoroughly exercises alg.m. The former can be used to quickly define input types, and the latter should be used when checking for run-time issues.
I have the problem, that I have to access a funktion form a dll in matlab/Simulink in the rtw.
This should work with a s function, but I have the needed parameters in a array of structures organized.
The question is now how I can reach them when I want to call my DLL function?
Or is there a better way (e.g. level 2 Matlab files or something similar)?
The pure simulation (without RTW) worked pretty well with level 2 m files but I am not able to write a tlc file for compiling them. I did not find much on the net and the documentation only about C sources.
Thanks
Christian
For signals in Simulink, what you are asking for is an array of buses. There is similar support for using arrays of structs for parameters. For calling an external function, you might want to look at the legacy code tool. You might also be able to use the MATLAB function block to call your external dll.
In addition to what #MikeT says:
Generating code from Level 2 M-S-Functions is problematic. Read this: http://www.mathworks.co.uk/help/toolbox/simulink/sfg/f7-67622.html#brgscav-1
Also, M-S-functions are generally slow, because they run in the MATLAB interpreter: http://blogs.mathworks.com/seth/2010/10/28/tips-for-simulation-performance/
In the end I coded the problem in C and used an array where I defined to order of the elements. Then I wrote some interface functions to access this "virtual" struct.
This is not very good coding but the easiest way I have found and it is portable.
Thanks
How to find out about a particular function or class in which version of Matlab/toolbox it was first introduced? I know I can look through all Release Notes, or Google can help sometime, but is there any better way?
Ditto Jonas ... there is no version history for specific functions.
One other thing you can do (if you didn't know this already) is, in your current version of Matlab, to check the value of exist('func'), where func is the name of the MATLAB function. The value this returns for matlab functions is 2, and for built-in functions it's 5.
If you're going for compatibility in your scripts, I would put a condition to check for that function existence before you use it. Otherwise, if you have multiple versions of MATLAB you can run a script to go through all of them or just do it by hand.
There isn't.
Except, if the place you work at has an active service contract with The MathWorks, you can send a service request and have them do the searching for you (be prepared to argue a bit if they just tell you to google the answer yorself). I do that from time to time in the hope that they'll eventually update the documentation.