Matlab Create Symbolic Links To Matlab Scripts

[Marilu Mandez]

Selectthe destination for symbolic links to MATLAB scripts. MATLAB sends user experience information to MathWorks by default. Uncheck the box if you do not want to participate in providing the information. Click Next.

This example follows the steps described in Generate C Code by Using the MATLAB Coder App (MATLAB Coder), but updates the steps to generate a MATLAB function from a symbolic expression. Alternatively, you can generate C code from a MATLAB function at the MATLAB command line by using the codegen (MATLAB Coder) command. For a tutorial on this workflow, see Generate C Code at the Command Line (MATLAB Coder).

Next, convert the two eigenvalues E(1) and E(2) to a MATLAB function file by using matlabFunction. Write the resulting function, which returns two elements E1 and E2, to the file myEigenvalues.m. Specify the order of input arguments as [q Omega delta].

The converted function in the file myEigenvalues.m can be used without Symbolic Math Toolbox. The MATLAB file myEigenvalues.m contains the function myEigenvalues that implements the core algorithm in this example. The function takes q, Omega, and delta as inputs, all of which must be either the same size or a scalar. It then calculates the two eigenvalues as a function of these inputs.

To make your MATLAB code suitable for code generation, use the Code Analyzer and the Code Generation Readiness Tool. The Code Analyzer in the MATLAB Editor continuously checks your code as you enter it. It reports issues and recommends modifications to improve performance and maintainability. The Code Generation Readiness Tool screens the MATLAB code for features and functions that are not supported for code generation.

The Code Analyzer message indicator in the top right corner of the MATLAB Editor is green. The analyzer did not detect errors, warnings, or opportunities for improvement in the code. For more information about using the Code Analyzer, see Check Code for Errors and Warnings Using the Code Analyzer.

In the Select Source Files page, enter or select the name of the entry-point function myEigenvalues. An entry-point function is a top-level MATLAB function from which you generate code. The app creates a project with the default name myEigenvalues.prj in the current folder.

Click Next to go to the Define Input Types step. The app runs the Code Analyzer, which you already ran in the previous step, and the Code Generation Readiness Tool on the entry-point function. If the app identifies issues, it opens the Review Code Generation Readiness page where you can review and fix issues. In this example, because the app does not detect issues, it opens the Define Input Types page. For more information, see Code Generation Readiness Tool (MATLAB Coder).

Note that the Code Analyzer and the Code Generation Readiness Tool might not detect all code generation issues. After eliminating the errors or warnings that these two tools detect, generate code with MATLAB Coder to determine if your MATLAB code has other compliance issues.

Certain MATLAB built-in functions and toolbox functions, classes, and System objects that are supported for C/C++ code generation have specific code generation limitations. These limitations and related usage notes are listed in the Extended Capabilities sections of their corresponding reference pages. For more information, see Functions and Objects Supported for C/C++ Code Generation (MATLAB Coder).

Because C uses static typing, the code generator must determine the class, size, and complexity of all variables in the MATLAB files at code generation time, also known as compile time. Therefore, you must specify the properties of all entry-point function inputs. To specify input properties, you can:

The Check for Run-Time Issues step generates a MEX function from your entry-point functions, runs the MEX function, and reports issues. A MEX function is generated code that can be called from inside MATLAB. Performing this step is a best practice because you can detect and fix run-time errors that are harder to diagnose in the generated C code. By default, the MEX function includes memory integrity checks. These checks perform array bounds and dimension checking. The checks detect violations of memory integrity in code generated for MATLAB functions. For more information, see Control Run-Time Checks (MATLAB Coder).

To convert MATLAB code to efficient C/C++ source code, the code generator introduces optimizations that, in certain situations, cause the generated code to behave differently than the original source code. See Differences Between Generated Code and MATLAB Code (MATLAB Coder).

In the Check for Run-Time Issues dialog box, specify a test file or enter code that calls the entry-point function with example inputs. For this example, use the test file myTest that you used to define the input types.

Click Check for Issues. The app generates a MEX function that can be run inside MATLAB. This step runs the test script myTest replacing calls to myEigenvalues with calls to the generated MEX function, that is [E1,E2] = myEigenvalues_mex(qGrid,OmegaGrid,delta). The generated MEX file myEigenvalues_mex is located in the folder work\codegen\lib\myEigenvalues (on Microsoft Windows platforms) or work/codegen/lib/myEigenvalues (on Linux or Mac platforms), where work is the location of myEigenvalues.m and myTest.m. If the app detects issues during the MEX function generation or execution, it provides warning and error messages. Click these messages to navigate to the problematic code and fix the issue. In this example, the app does not detect issues.

By default, the app collects line execution counts. These counts help you see how well the test file myTest.m exercised the myEigenvalues function. To view line execution counts, click View MATLAB line execution counts. The app editor displays a color-coded bar to the left of the code. To extend the color highlighting over the code and to see line execution counts, place your cursor over the bar. A particular shade of green indicates that the code only executes one call to compute the eigenvalues.

Click Generate. MATLAB Coder generates a standalone C static library, myEigenvalues, in the folder work\codegen\lib\myEigenvalues. The folder work is the location of myEigenvalues.m and myTest.m. The MATLAB Coder app indicates when code generation has succeeded. It displays the source MATLAB files and generated output files on the left side of the page. On the Variables tab, it displays information about the MATLAB source variables. On the Target Build Log tab, it displays the build log, including C/C++ compiler warnings and errors. By default, the code window displays the C source code file, myEigenvalues.c. To view a different file, click the desired file name in the Source Code or Output Files pane.

Click View Report to view the report in the Report Viewer. If the code generator detects errors or warnings during code generation, the report describes the issues and provides links to the problematic MATLAB code. For more information, see Code Generation Reports (MATLAB Coder).

const double q[32768] and const double Omega[32768] corresponds to the input q and Omega in your MATLAB code. The size of q is 32768, which corresponds to the total size (128 x 256) of the example input that you used when you generated C/C++ code from your MATLAB code. The same applies to the input Omega. In this case, the generated code uses one-dimensional arrays to represent two-dimensional arrays in the MATLAB code.

The code generator preserves your function name and comments. When possible, the code generator preserves your variable names. Note that if a variable in your MATLAB code is set to a constant value, it does not appear as a variable in the generated C code. Instead, the generated C code contains the value of the variable as a literal.

The C function that you generated for myEigenvalues.m can accept only inputs that have the same size as the sample inputs that you specified during code generation. However, the input arrays to the corresponding MATLAB function can be of any size. In this part of the example, you generate C code from myEigenvalues.m that accepts variable-size inputs.

The C code now consists of a data structure called an emxArray_real_T to represent an array whose size is unknown and unbounded at compile time. For more details, see Use C Arrays in the Generated Function Interfaces (MATLAB Coder).

I have a utility consisting of a couple of directories with some bash scripts and supporting files that will be deployed to several machines, possibly in a different directory on each machine. The scripts need to be able to reference paths relative to themselves, so I need to be able to get the path to the file that's currently being executed.

I am aware of the dirname $0 idiom which works perfectly when my script is called directly. Unfortunately there is a desire to be able to create symlinks to these scripts from a totally different directory and still have the relative pathing logic work.

Use symbolic links to alias paths. This is useful if you have numerous hardcoded paths that would be time-consuming to change manually.

Consider the following shell script - called run.sh on Code Ocean:

The ln -s command creates a link that points to /data where the code might otherwise look for files in /code/input_images. If your input images were in a folder called input_images and they are now in /data, the code will find them in the new location.

MATLAB, or Matrix Laboratory, is a programming and numeric computing platform used by millions of engineers and scientists to analyze data, develop algorithms, create models, and provide visual insights. It is a staple for any sort of complex numerical or mathematical programming, which makes it a valuable tool for research, development, and innovation.

MATLAB is available for installation on almost all of the leading operating systems (OS), such as Microsoft Windows, Mac, and Linux. In this article, we will learn how to install and run MATLAB on Linux.

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