Problem using emxArray_real_T from Matlab Coder

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Carlos
Carlos 2013-8-26
编辑： Ryan Livingston 2015-1-6
Hi all,
I am trying to learn how to use standalone C++ code from Matlab. I have created a very simple function that takes only one argument, which is a vector of size (N,1), where N is unknown a priori. Therefore, I have to use dynamic allocated memory, if I am not wrong. The generated C++ code takes two arguments, of type emxArray_real_T, where x is the input vector, and yout the output vector,
void fun4(const emxArray_real_T *x, emxArray_real_T *yout)
{
...
}
Now, I am trying to create the input vector, and to run the function, but I think that I have no idea how to do it. I have read the answer in http://www.mathworks.com/matlabcentral/answers/67237-matlab-coder-segmentation-fault , but I think it is not so clear to me. This is what I am trying to do,
int main()
{
double datax[3];
double result[3] = {};
emxArray_real_T *inputs, *outputs;
for (int n=0; n<3; n++)
{
datax[n] = n;
}
inputs = emxCreateWrapper_real_T(&datax, 1, 3);
outputs = emxCreateWrapper_real_T(&result, 1, 3);
fun4(inputs, outputs);
return 0;
}
but I always get compilation errors,
cannot convert ‘double (*)[3]’ to ‘real_T* {aka double*}’ for argument ‘1’ to ‘emxArray_real_T* emxCreateWrapper_real_T(real_T*, int32_T, int32_T)’
Since I am not an expert on C++, I was wondering if anyone can teach me how to pass the input vector, and to recover the results... Thank you very much in advance!

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采纳的回答

Ryan Livingston
Ryan Livingston 2013-8-27
编辑：Ryan Livingston 2015-1-6
Try using:
emxCreateWrapper_real_T(datax, 1, 3)
The compiler is complaining because
datax
is usually treated as a pointer to the first element of datax. Therefore
&datax
is a pointer to an array of 3 doubles rather than a pointer to a single double as fun4 requires. This is the difference between
double (*)[3] //pointer to array of 3 doubles
and
double * //pointer to one double
  1 个评论
Carlos
Carlos 2013-8-27
It worked!! Thank you very much! I thought I was driving crazy. Although, honestly, I was expecting something much more complicated... so now I feel a bit stupid :D As you can see, I am not really quite knowledgeable about C++ yet.

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更多回答（1 个）

Imran
Imran 2015-1-5
编辑：Imran 2015-1-6
I have the same Issue
In my case I need to get out put as a Array of 2 rows and six column
so I am facing the the problem in line
outputs = emxCreateWrapper_real_T(data, 6, 2);
Could you please guide me.
I am currently running program as follows
int main()
{ double strem[12];
double data[2][6];
emxArray_real_T *inputs, *outputs;
for (int n=0; n<13; n++)
{
strem[n] = n;
}
inputs = emxCreateWrapper_real_T(strem, 1,12);
outputs = emxCreateWrapper_real_T(data, 6, 2);
charrang(inputs, outputs);
return 0;
}

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