#include <stdio.h>#include <ctype.h>#include "mex.h"#if MX_API_VER < 0x07030000typedef int mwIndex;#endif void exit_with_help(){	mexPrintf(	"Usage: [label_vector, instance_matrix] = read_sparse(fname);\n"	);}static void fake_answer(mxArray *plhs[]){	plhs[0] = mxCreateDoubleMatrix(0, 0, mxREAL);	plhs[1] = mxCreateDoubleMatrix(0, 0, mxREAL);}// read in a problem (in svmlight format)void read_problem(const char *filename, mxArray *plhs[]){	int elements, max_index, min_index, i, k;	FILE *fp = fopen(filename,"r");	int l = 0;	mwIndex *ir, *jc;	double *labels, *samples;		if(fp == NULL)	{		mexPrintf("can't open input file %s\n",filename);		fake_answer(plhs);		return;	}	max_index = 0;	min_index = 1; // our index starts from 1	elements = 0;	while(1)	{		// label		int index;		double value;		fscanf(fp,"%lf",&value);		// features		while(1)		{			int c;			do {				c = getc(fp);				if(c=='\n') goto out;				if(c==EOF) goto eof;			} while(isspace(c));			ungetc(c,fp);			fscanf(fp,"%d:%lf",&index, &value);			if (index < min_index)				min_index = index;			elements++;		}	out:		if(index > max_index)			max_index = index;		l++;	}eof:	rewind(fp);	// y	plhs[0] = mxCreateDoubleMatrix(l, 1, mxREAL);	// x^T	if (min_index <= 0)		plhs[1] = mxCreateSparse(max_index-min_index+1, l, elements, mxREAL);	else		plhs[1] = mxCreateSparse(max_index, l, elements, mxREAL);	labels = mxGetPr(plhs[0]);	samples = mxGetPr(plhs[1]);	ir = mxGetIr(plhs[1]);	jc = mxGetJc(plhs[1]);	k=0;	for(i=0;i<l;i++)	{		jc[i] = k;		fscanf(fp,"%lf",&labels[i]);		while(1)		{			int c, index;			do {				c = getc(fp);				if(c=='\n') goto out2;			} while(isspace(c));			ungetc(c,fp);			fscanf(fp,"%d:%lf",&index,&samples[k]);			ir[k] = index - min_index; // precomputed kernel has <index> start from 0			++k;		}	out2:		;	}	jc[l] = k;	fclose(fp);	{		mxArray *rhs[1], *lhs[1];		rhs[0] = plhs[1];		if(mexCallMATLAB(1, lhs, 1, rhs, "transpose"))		{			mexPrintf("Error: cannot transpose problem\n");			return;		}		plhs[1] = lhs[0];	}}void mexFunction( int nlhs, mxArray *plhs[],		int nrhs, const mxArray *prhs[] ){	if(nrhs == 1)	{		char filename[256];		mxGetString(prhs[0], filename, mxGetN(prhs[0]) + 1);		if(filename == NULL)		{			mexPrintf("Error: filename is NULL\n");			return;		}		read_problem(filename, plhs);	}	else	{		exit_with_help();		fake_answer(plhs);		return;	}}