diff --git a/auxiliary/m_aux_lib.c b/auxiliary/m_aux_lib.c
new file mode 100644
index 0000000..30cb333
--- /dev/null
+++ b/auxiliary/m_aux_lib.c
@@ -0,0 +1,112 @@
+/**************************************************************************************************
+*                                                                                                 *
+* This file is part of BLASFEO.                                                                   *
+*                                                                                                 *
+* BLASFEO -- BLAS For Embedded Optimization.                                                      *
+* Copyright (C) 2016-2017 by Gianluca Frison.                                                     *
+* Developed at IMTEK (University of Freiburg) under the supervision of Moritz Diehl.              *
+* All rights reserved.                                                                            *
+*                                                                                                 *
+* HPMPC is free software; you can redistribute it and/or                                          *
+* modify it under the terms of the GNU Lesser General Public                                      *
+* License as published by the Free Software Foundation; either                                    *
+* version 2.1 of the License, or (at your option) any later version.                              *
+*                                                                                                 *
+* HPMPC is distributed in the hope that it will be useful,                                        *
+* but WITHOUT ANY WARRANTY; without even the implied warranty of                                  *
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.                                            *
+* See the GNU Lesser General Public License for more details.                                     *
+*                                                                                                 *
+* You should have received a copy of the GNU Lesser General Public                                *
+* License along with HPMPC; if not, write to the Free Software                                    *
+* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA                  *
+*                                                                                                 *
+* Author: Gianluca Frison, giaf (at) dtu.dk                                                       *
+*                          gianluca.frison (at) imtek.uni-freiburg.de                             *
+*                                                                                                 *
+**************************************************************************************************/
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+
+#include "../include/blasfeo_common.h"
+
+
+
+#if defined(LA_REFERENCE) | defined(LA_BLAS)
+
+
+
+
+void m_cvt_d2s_strvec(int m, struct d_strvec *vd, int vdi, struct s_strvec *vs, int vsi)
+	{
+	double *pd = vd->pa+vdi;
+	float *ps = vs->pa+vsi;
+	int ii;
+	for(ii=0; ii<m; ii++)
+		{
+		ps[ii] = (float) pd[ii];
+		}
+	return;
+	}
+
+
+
+void m_cvt_s2d_strvec(int m, struct s_strvec *vs, int vsi, struct d_strvec *vd, int vdi)
+	{
+	double *pd = vd->pa+vdi;
+	float *ps = vs->pa+vsi;
+	int ii;
+	for(ii=0; ii<m; ii++)
+		{
+		pd[ii] = (double) ps[ii];
+		}
+	return;
+	}
+
+
+
+void m_cvt_d2s_strmat(int m, int n, struct d_strmat *Md, int mid, int nid, struct s_strmat *Ms, int mis, int nis)
+	{
+	int lda = Md->m;
+	int ldb = Ms->m;
+	double *pA = Md->pA+mid+nid*lda;
+	float *pB = Ms->pA+mis+nis*ldb;
+	int ii, jj;
+	for(jj=0; jj<n; jj++)
+		{
+		for(ii=0; ii<m; ii++)
+			{
+			pB[ii+jj*ldb] = (float) pA[ii+jj*lda];
+			}
+		}
+	return;
+	}
+
+
+
+void m_cvt_s2d_strmat(int m, int n, struct s_strmat *Ms, int mis, int nis, struct d_strmat *Md, int mid, int nid)
+	{
+	int lda = Ms->m;
+	int ldb = Md->m;
+	float *pA = Ms->pA+mis+nis*lda;
+	double *pB = Md->pA+mid+nid*ldb;
+	int ii, jj;
+	for(jj=0; jj<n; jj++)
+		{
+		for(ii=0; ii<m; ii++)
+			{
+			pB[ii+jj*ldb] = (double) pA[ii+jj*lda];
+			}
+		}
+	return;
+	}
+
+
+
+#else
+
+#error : wrong LA choice
+
+#endif