Project Chrono: Matlab engine example (demo_MTLB_matlab.cpp)

Matlab engine example (demo_MTLB_matlab.cpp)

Entry level demo about how to use Matlab(TM) and the MATLAB module to plot Chrono::Engine data, to perform computations, etc.

This example requires that you own a copy of Matlab(TM), properly installed on your system (if you do not have Matlab(TM) installed and you try to execute demo_matlab.exe, it will give an error because it cannot load the Matlab engine dll).

This tutorial shows how to:

- do basic interaction with Matlab (copy matrices from/to Matlab workspace)
- plot data using Matlab.

// =============================================================================
// PROJECT CHRONO - http://projectchrono.org
//
// Copyright (c) 2014 projectchrono.org
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be found
// in the LICENSE file at the top level of the distribution and at
// http://projectchrono.org/license-chrono.txt.
//
// =============================================================================
// Authors: Alessandro Tasora
// =============================================================================
//
// Demonstration on how to call Matlab from Chrono::Engine
//
// =============================================================================
#include "chrono_matlab/ChMatlabEngine.h"
// Use the namespace of Chrono
using namespace chrono;
int main(int argc, char* argv[]) {
std::cout << "Copyright (c) 2017 projectchrono.org\nChrono version: " << CHRONO_VERSION << std::endl;
// Better put the Matlab stuff inside a try{}, since it may throw exception if
// the engine is not started (because Matlab not properly installed)
try {
std::cout << "PERFORM TESTS OF MATLAB<->CHRONO INTERACTION\n\n";
std::cout << "(please wait few seconds: Matlab engine must be loaded)\n\n";
// This is the object that you can use to access the Matlab engine.
// As soon as created, it loads the Matlab engine (if troubles happen, it
// throws exception).
ChMatlabEngine matlab_engine;
//
// EXAMPLE 1: execute a Matlab command
//
std::cout << "- Execute plotting command from Chrono...\n\n";
matlab_engine.Eval(
"z=peaks(25); \
surf(z); \
colormap(jet); \
pause(4); \
");
//
// EXAMPLE 2: pass a Chrono matrix to Matlab
//
std::cout << "- Send some data to Matlab for operations and plotting...\n\n";
ChMatrixDynamic<> m_time(30, 1);
ChMatrixDynamic<> m_sine(30, 1);
for (int i = 0; i < 30; i++) {
m_time(i, 0) = ((double)i / 30.) * 5.;
m_sine(i, 0) = sin(m_time(i, 0) * 2.);
}
matlab_engine.PutVariable(m_time, "m_time");
matlab_engine.PutVariable(m_sine, "m_sine");
matlab_engine.Eval("figure; plot(m_time,m_sine);");
//
// EXAMPLE 3: pass a Matlab matrix to Chrono
//
std::cout << "- Fetch some data from Matlab...\n\n";
matlab_engine.Eval("m_matr=[0:0.1:5]';");
ChMatrixDynamic<double> m_matr;
matlab_engine.GetVariable(m_matr, "m_matr");
std::cout << m_matr << std::endl;
//
// EXAMPLE 4: pass a sparse matrix to Matlab
//
std::cout << "- Send a sparse matrix to Matlab...\n\n";
ChSparseMatrix m_sparse(6, 7);
m_sparse.SetElement(3, 5, 102);
m_sparse.SetElement(1, 2, 104);
m_sparse.SetElement(4, 4, 101);
matlab_engine.PutSparseMatrix(m_sparse, "m_sparse");
matlab_engine.Eval("figure; spy(m_sparse);");
// Wait some seconds before closing all
matlab_engine.Eval("pause(60)");
} catch (std::exception mex) {
std::cerr << mex.what() << std::endl; // Print error on console, if Matlab did not start.
}
system("pause");
return 0;
}
chrono::ChMatlabEngine
Class for accessing the Matlab engine with a C++ wrapper.
Definition ChMatlabEngine.h:45
chrono::ChMatlabEngine::GetVariable
bool GetVariable(ChMatrixDynamic< double > &mmatr, std::string varname)
Fetch a matrix from Matlab environment, specifying its name as variable.
Definition ChMatlabEngine.cpp:120
chrono::ChMatlabEngine::Eval
bool Eval(std::string mstring)
Evaluate a Matlab instruction (as a string). If error happens while executing, returns false.
Definition ChMatlabEngine.cpp:63
chrono::ChMatlabEngine::PutVariable
bool PutVariable(ChMatrixConstRef mmatr, std::string varname)
Put a matrix in Matlab environment, specifying its name as variable.
Definition ChMatlabEngine.cpp:72
chrono::ChMatlabEngine::PutSparseMatrix
bool PutSparseMatrix(const ChSparseMatrix &mmatr, std::string varname)
Put a sparse matrix in Matlab environment, specifying its name as variable.
Definition ChMatlabEngine.cpp:86
chrono::ChMatrixDynamic
Eigen::Matrix< T, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor > ChMatrixDynamic
Dense matrix with dynamic size (i.e., with unknown at compile time) and row-major storage.
Definition ChMatrix.h:75
chrono::ChSparseMatrix
Eigen::SparseMatrix< double, Eigen::RowMajor, int > ChSparseMatrix
Sparse matrix representation.
Definition ChMatrix.h:185
chrono
Main namespace for the Chrono package.
Definition ChCamera.cpp:17