As there is a MATLAB compiler to C, I am wondering if there is a compiler of converter that can convert some of the mathematical C/C++ codes to MATLAB?
I know that many of the capabilities and functions in C/C++ are not available in MATLAB, but at least for purely mathematical codes, is there any convertor tool out there?
Look into Mex-files:
http://www.mathworks.com/help/techdoc/ref/mex.html
With it, you can write C or C++ and call it in Matlab, allowing to use facilities or code provided/already written in C or C++ in Matlab.
Related
related
My goal is to use a mix of C code and Matlab code, and ultimately have the whole thing run in C by using the Coder tool.
I've found 2 ways of incorporating C into Matlab, writing a Mex file, and using coder.ceval on a C program.
Is there any difference in these 2 methods, beyond just calling syntax?
I'll compare creating a hand-written MEX file against using MATLAB Coder to integrate custom C code using coder.ceval.
Similarities
In both cases, a MEX file can be produced that you can call in MATLAB like any other MATLAB function. A hand-written MEX function will be compiled using the mex command from C source code you write. With MATLAB Coder the MEX file will be automatically generated from MATLAB code that calls your C code via coder.ceval using either the codegen command or the MATLAB Coder App.
Some Basic Differences
(note I use C throughout, but C++ can be used for MEX files as well)
When writing a MEX file, it is necessary to manually move your data between mxArray values and native C types. You'll need to use the MEX library and the C/C++ Matrix Library to do this. If coder.ceval is used, a MEX file can be auto-generated from your MATLAB code that does this data marshalling for you.
A single hand-written MEX file can be made to work with a variety of MATLAB data types. MATLAB Coder requires the type, size (arrays can also be made variable-size), and complexity of each argument to be declared. For example, if you want a MEX file that takes double and single values for a given input, then one MEX file must be generated for each input type.
With a handwritten MEX file, once the data is retrieved from the mxArray values provided by MATLAB, arbitrary C code can be written to manipulate it. coder.ceval requires that you write MATLAB Coder compatible MATLAB code to call the C functions using the external code interfaces it provides. For functions with simple interfaces, e.g. those taking numeric arrays, strings, etc., this can be simple. For those that take other datatypes, more advanced tools like coder.opaque, coder.cstructname and custom enumeration definitions must be used which can take time. One needs to weigh the cost of developing this interface for MATLAB Coder versus learning and using the MATLAB libraries mentioned in the first bullet.
If you eventually want to use the code in C outside of MATLAB, with MATLAB Coder and coder.ceval, the target can simply be changed from MEX to a standalone target like a static or dynamic library or executable. With a handwritten MEX file, one typically factors the C code so that the MEX interface, mexFunction, is separate from the C functional kernel. Then, this kernel can be called outside of MEX. If you are planning to use MATLAB Coder anyway, you'll have to integrate the MATLAB Coder code with this kernel somehow.
If the code is to be used with MATLAB Coder eventually, calling MEX files using Coder when the target is MEX requires using coder.extrinsic. They also cannot be called directly in standalone targets. Instead, the C computational kernel underlying the MEX file needs to be integrated with the generated code either during code generation using coder.ceval or after code generating using a traditional C development environment.
Factors to Consider When Deciding
Do the benefits of integrating the C code early using MATLAB Coder and having the MEX interface auto-generated outweigh the work required to use the MATLAB Coder external code interfaces versus a hand-written MEX file?
Is integrating the external C code using coder.ceval easier or harder than writing a MEX file that exposes it to MATLAB and then later integrating your MATLAB Coder generated code with the computational kernel underlying your MEX file?
I have some code that plots triangles in MATLAB.
I need to be able to somehow execute this code from my C program which generates these points.
Is that possible? How can it be done?
Just a thought:
Can I somehow embed MATLAB code in C, so that it can compile on a C compiler?
The Mathworks site has full details; a demo video of calling the Matlab engine from C, and also the Matlab to C Compiler.
As mentioned previously by answerers, you can call a live copy of MATLAB from C via the MATLAB Engine interface.
If the end-product needs to be used where there is no live copy of MATLAB, you can deploy the application using MATLAB Compiler. However, MATLAB Compiler does not, as another answer has suggested, convert MATLAB programs into C code (and hasn't done for a few versions now). Instead, it archives and encrypts your MATLAB program, and packages it into an executable or shared library that executes against the MATLAB Compiler Runtime (shareable royalty-free). The executable or shared library can then be called from C.
Alternatively you could go the other way around, and call your C code from MATLAB, using either loadlibrary or MATLAB's MEX interface.
Update: As of release R2011a, you can also use MATLAB Coder to generate C code directly from a subset of the MATLAB language.
Look at this presentation about integrating MATLAB Algorithms in C or C++ Applications http://www.mathworks.com/videos/integrating-matlab-algorithms-in-c-or-c-applications-86431.html
I don't know very much about template programming, and I currently use gsl. I'm interested in seeing if Eigen can be use in C. Has anybody used Eigen in C before? Is there something I can test to find out if it will be easy?
Since Eigen is a C++ template library, it cannot be directly used with C.
Hypothetically, one could wrap the C++ templates into a C API, and use that. However, that's bound to involve a lot of work and would strike me as a bit pointless (one might as well use existing C libraries for linear algebra).
AFAIK, Eigen is a template-only library. C doesn't support templates. So without writing a bunch of wrapper functions that expose a C-style interface, no.
I'm sorry if this is a basic question(I'm new to c/c++, but I'm a little confused at how to get the answer. stxxl is a c++ library but some of my code is in c. I know c++ can use c code(my c code is embedded in c++), but does it work the other way around so c can run c++ code?
Their site only mentions c++ but I'm wondering if there's something special that can be done to run c++ libraries within c?
Sorry the books I have read talk about using c code in c++ and the c book I read was written before c++ came out. Right now my c function is sending data to my c++ code which is using the c++ library and then sending results back so I'm thinking I want to test performance if I cut the middle man(c++).
You can link to a C++ library from C only when the C++ library has been designed to be used from C. Specifically, the functions the library provides need to be exported with extern "C" {} block to avoid name mangling, and the interface should be designed in a way to be usable from plain C (i.e. no classes or member functions, only functionless structs and plain functions).
It is worth mentioning that you can compile your C code with a C++ compiler, and it will for the most part be OK. This lets you pretend that your C code is a C++ code, and freely mix in functionality provided through C++ - specific interfaces.
Here's a links that may help you:
How to mix C and C++
Hi I wanted to know how to use MATLAB as an external solver from a C program. Specifically in my code I wish
to solve several linear systems of the form Ax=b.
I have heard that to go the other way namely Calling C functions in a MATLAB routine one uses MEX files.But I am not really sure how to use Mex files either.
Thank you
Actually, MEX files allow you to include C code in Matlab programs, for example if you want to use external C libraries in Matlab.
What you want to do is use the Matlab Engine:
http://www.mathworks.com/help/techdoc/matlab_external/f29148.html
As an alternative, you could use linear algebra libraries that are written purely in C, such as LAPACK and BLAS. ( www.netlib.org )
you can use the matlab engine as Lagerbaer points out. However sometimes it can be convenient just calling the matlab process commandline style. I use this often when I don't want to mess with mxArrays etc, or when the amount of matlab code that needs executing gets really large. PseudoCode:
WriteArrayInMFormat( "in.m", myInputNumbers );
LaunchProcess( "matlab", "-nodesktop -r \"myFunction( 'in.m' )\" -logfile out.m" );
ReadArrayInMFormat( "out.m", myResult );
For me this is especially useful when testing things out: instead of having to recompile the C/C++ program each time I change something, I just apply all changes in the myFunction.m file. At that point I don't even need the C program, instead everything can be tested in matlab.