如何从mex函数返回浮点值，以及如何从m文件中检索它? [英] How to return a float value from a mex function, and how to retrieve it from m-file?

问题描述

我知道mex函数的所有返回值都存储在mxArray *类型的plhs数组中.我想返回一个float类型的值.我该怎么办?

I understand that all the returned values of a mex function are stored in plhs array of type mxArray*. I want to return a value of type float. How can I do it?

从mex函数返回它并从m文件中检索它的一些代码示例受到人们的赞赏.

Some code examples on returning it from the mex function and retrieving it from the m-file is much appreciated.

推荐答案

浮点类型数据的MATLAB类名称为单个".

The MATLAB class name for float type data is "single".

在MEX文件中，您可以编写:

In the MEX-file you could write:

void mexFunction(int nlhs, mxArray * plhs[], int nrhs, const mxArray * prhs[])
{
    // Create a 2-by-3 real float
    plhs[0] = mxCreateNumericMatrix(2, 3, mxSINGLE_CLASS, mxREAL);

    // fill in plhs[0] to contain the same as single([1 2 3; 4 5 6]); 
    float * data = (float *) mxGetData(plhs[0]);
    data[0] = 1; data[1] = 4; data[2] = 2; 
    data[3] = 5; data[4] = 3; data[5] = 6;
}

从M文件中检索它非常类似于调用任何其他函数.如果您将MEX函数命名为foo，则将其命名为:

Retrieving it from the M-file is pretty much like calling any other function. If you named the MEX-function foo, you'd call it like this:

>> x = foo;

现在x将包含与single([1 2 3; 4 5 6])等效的单精度值，该值存储在plhs[0]中.

Now x would contain the single-precision value equivalent to single([1 2 3; 4 5 6]) that was stored in plhs[0].

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