gistfile1.cpp

void cvPolyfit( CvMat* src_x, CvMat* src_y,  CvMat *dst, int order )
{
	CvMat* X = cvCreateMat( src_x->rows, order+1, CV_32FC1 );
	for(int i=0;i<=order;i++)
	{
		CvMat* cpy = cvCloneMat( src_x );
		cvPow( cpy, cpy, (double)i );
		for (int j=0;j<src_x->rows;j++)
			cvmSet( X, j, i, cvmGet( cpy, j, 0 ) );

		cvReleaseMat(&cpy);
	}	
	
	CvMat* X_t = cvCreateMat( X->cols, X->rows, CV_32FC1 );
	cvTranspose( X, X_t );
	CvMat* tmp = cvCreateMat( X_t->rows, X->cols, CV_32FC1 );	
	cvMatMul( X_t, X, tmp );
	CvMat* tmp_inv = cvCloneMat( tmp );
	cvInvert( tmp, tmp_inv );
	CvMat* tmp3 = cvCreateMat( tmp_inv->rows, X_t->cols, CV_32FC1 );	
	cvMatMul( tmp_inv, X_t, tmp3 );
	cvMatMul( tmp3, src_y, dst );
	cvReleaseMat(&X);
	cvReleaseMat(&X_t);
	cvReleaseMat(&tmp);
	cvReleaseMat(&tmp_inv);
	cvReleaseMat(&tmp3);
}