小白问个问题，关于C++和matlab混用

c++文件：sort_sparse_mat.cpp
#include <iostream>
#include <string>
#include <vector>#include <mex.h>#include "utils.h"
#include "mat.h"
#include "mex_utils.h"#define llint long long intusing namespace std;void mexFunction(int nlhs, mxArray* plhs[], int nrhs, const mxArray* prhs[])
{
// Sorts the columns of a sparse matrix (ascending/descending) and outputs sorted value and index matrices massert(nrhs>=1 && nrhs<=2, "Allowed inputs: <matrix to sort>,<sort order ('ascend' or 'descend'), default='descend'>");
massert(nlhs==1,"Exactly 1 output allowed: <rank-matrix>"); string order = "descend";
if(nrhs>1)
order = mxArrayToString(prhs[1]);
massert(order=="ascend" || order=="descend", "2nd parameter should be either 'ascend' or 'descend'"); mxArray* inarr = (mxArray*)prhs[0];
mwIndex* inIr = mxGetIr(inarr);
mwIndex* inJc = mxGetJc(inarr);
double* inPr = mxGetPr(inarr); mxArray* outarr = mxDuplicateArray(inarr);
mwIndex* outIr = mxGetIr(outarr);
mwIndex* outJc = mxGetJc(outarr);
double* outPr = mxGetPr(outarr); vector<pair<llint,double>> vec;
for(int i=0; i<mxGetN(inarr); i++)
{
vec.clear();
for(llint j=inJc[i]; j<inJc[i+1]; j++)
vec.push_back(make_pair(j,inPr[j])); if(order == "ascend")
sort(vec.begin(),vec.end(),comp_pair_by_second<llint,double>);
else if(order == "descend")
sort(vec.begin(),vec.end(),comp_pair_by_second_desc<llint,double>); for(int j=0; j<vec.size(); j++)
outPr[vec[j].first] = j+1;
} plhs[0] = outarr;
}
运行语句mex -v CXXFLAGS='$CXXFLAGS -std=c++11 -O3' -largeArrayDims sort_sparse_mat.cpp后，
系统生成了一个sort_sparse_mat.mexw64文件。
问题是怎么调用这个sort_sparse_mat啊，这程序是肯定没有问题的
我直接输入sort_sparse_mat(a)总是报错