在C ++代码中调用Matlab - 使用engine.h中的方法 [英] Call Matlab in C++ code - using methods in engine.h

问题描述

我写一个C ++程序，其唯一的目的是调用Matlab代码。我有一个主程序，将

1. 将文件（高维度为90000 * 24的矩阵）中的数据读入C ++
   结构




2. 将这些结构传递到Matlab代码




3. 这些结构在参数




4. 中获取来自Matlab的输出数据并将其存储在C ++结构中

在2 /中，矩阵是Matlab结构中的字段。该结构，例如 MATLAB_STRUCT 有几个矩阵字段， MATLAB_STRUCT.Z1 ， MATLAB_STRUCT.Z2 ，...和一些浮动字段 MATLAB_STRUCT.flt1 ，...

是将C ++矩阵（ double ** ）设置为Matlab结构的字段的正确方法？到目前为止，我想出了这个，使用 engine.h

  mxArray * labcoeffs_array = convertVectorToMxArray（labcoeffs，
 coeff_nrows，coeff_ncols）; 
 const std :: string lab_coeff_name =MATLAB_STRUCT.labCoef; 
 engPutVariable（ep，lab_coeff_name.c_str（），labcoeffs_array）; 
  

其中 convertVectorToMxArray 将 double ** 转换为 mxArray ，

  inline mxArray * convertVectorToMxArray（double ** mat，
 const int nb_rows，const int nb_cols）
 {
 mxArray * outputMxArray = mxCreateDoubleMatrix（
 int）nb_rows，
（int）nb_cols，
 mxREAL）; 
 
 double * data =（double *）mxGetData（outputMxArray）; 
 for（int r = 0; r  for（int c = 0; c  data [r + c * nb_rows] = double）mat [r] [c]; 
 
 return outputMxArray; 
}; 
  

但我已经看到了一些其他的技术用于在Cpp代码中为一个Matlab结构赋值但不是矩阵），在C ++字符串中模仿命令行语法：

  std :: string setStruct = MATLAB_STRUCT+。 +nB+=+ str-> nB +;; 
 matlabExecute（ep，setStruct）; 
  

与 ep 指向Matlab引擎。

• 是否可以使用命令行将此方法适用于为Matlab struct的矩阵类型字段赋值？




• 为Matlab结构的矩阵类型字段分配值的最佳方法是什么？






解决方案

要在结构中创建一个矩阵字段，一个选项是创建一个temp变量，然后将其值赋给一个字段的结构：

  //创建临时变量
 mxArray * array = convertVectorToMxArray（mat，nb_rows，nb_cols）; 
 const std :: string temp_name = array_name +_temp; 
 int ret = engPutVariable（ep，temp_name.c_str（），array）; 
 
 //将变量设置为struct字段
 const std :: string cmd = std :: string（array_name +=+ temp_name +;）; 
 matlabExecute（ep，cmd）; 
 
 //删除数组
 mxDestroyArray（array）; 
  




I write a C++ program whose only purpose is to call Matlab code. I have a main routine, which

1. read data in a file (matrices with high dimension 90000*24) into C++ structures

2. pass these structures to Matlab code

3. launch the Matlab routine with these structures in argument

4. get the output data from Matlab and store them in C++ structures

In 2/, matrices are fields in a Matlab struct. The struct, say MATLAB_STRUCT has several matrix fields, MATLAB_STRUCT.Z1, MATLAB_STRUCT.Z2,... and some float fields MATLAB_STRUCT.flt1,...

What is the correct approach to set C++ matrices (double**) as the fields of the Matlab struct? So far, I came up with this, using engine.h

    mxArray* labcoeffs_array = convertVectorToMxArray(labcoeffs, 
                                                         coeff_nrows, coeff_ncols); 
    const std::string lab_coeff_name = "MATLAB_STRUCT.labCoef";
    engPutVariable(ep, lab_coeff_name.c_str(), labcoeffs_array);

where convertVectorToMxArray is an helper I wrote to convert double** to a mxArray,

inline mxArray *convertVectorToMxArray(double** mat, 
                                              const int nb_rows, const int nb_cols)
{
    mxArray *outputMxArray = mxCreateDoubleMatrix(
        (int) nb_rows,
        (int) nb_cols,
        mxREAL);

    double *data = (double*) mxGetData(outputMxArray);
    for (int r = 0; r < nb_rows; r++)
        for (int c = 0; c < nb_cols; c++)
            data[r + c*nb_rows] = (double)mat[r][c];

    return outputMxArray;
};

But I have seen some other technique for assigning a value to a Matlab struct in the Cpp code (a float value though, not a matrix), imitating the command line syntax in a C++ string:

std::string setStruct = "MATLAB_STRUCT" + "." + "nB" + " = " + str->nB + ";";
matlabExecute(ep, setStruct);

with ep a pointer to a Matlab engine.

• Is it possible to adapt this approach with command line to assigning a value to a matrix type field of a Matlab struct?

• what is the best approach to assign a value to a matrix type field of a Matlab struct?

解决方案

To create a matrix field in a struct, one option is to create a temp variable, and then to assign its value to a field of the struct:

// Create temp variable
mxArray* array = convertVectorToMxArray(mat, nb_rows, nb_cols);  
const std::string temp_name = array_name + "_temp";
int ret = engPutVariable(ep, temp_name.c_str(), array);

// Set variable to struct field
const std::string cmd = std::string(array_name + " = " + temp_name + "; ");
matlabExecute(ep, cmd);

// Delete array
mxDestroyArray(array);

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