diff -up gdl-0.9.4/src/basic_op.cpp.eigen gdl-0.9.4/src/basic_op.cpp
--- gdl-0.9.4/src/basic_op.cpp.eigen	2013-09-21 21:09:10.000000000 -0600
+++ gdl-0.9.4/src/basic_op.cpp	2013-10-04 14:04:17.018256208 -0600
@@ -1543,8 +1543,8 @@ Data_<Sp>* Data_<Sp>::MatrixOp( BaseGDL*
       } 
     } 
     
-    Map<Matrix<Ty,-1,-1>,Aligned> m0(&(*this)[0], NbCol0, NbRow0);
-    Map<Matrix<Ty,-1,-1>,Aligned> m1(&(*par1)[0], NbCol1, NbRow1);
+    Map<Matrix<Ty,Dynamic,Dynamic>,Aligned> m0(&(*this)[0], NbCol0, NbRow0);
+    Map<Matrix<Ty,Dynamic,Dynamic>,Aligned> m1(&(*par1)[0], NbCol1, NbRow1);
 
     if (at && bt)
       {
@@ -1560,7 +1560,7 @@ Data_<Sp>* Data_<Sp>::MatrixOp( BaseGDL*
 	Data_* res = new Data_(dim, BaseGDL::NOZERO);
 	// no guarding necessary: eigen only throws on memory allocation
 
-	Map<Matrix<Ty,-1,-1>,Aligned> m2(&(*res)[0], NbCol2, NbRow2);
+	Map<Matrix<Ty,Dynamic,Dynamic>,Aligned> m2(&(*res)[0], NbCol2, NbRow2);
 	m2.noalias() = m0.transpose() * m1.transpose();
 	return res;
       } 
@@ -1576,7 +1576,7 @@ Data_<Sp>* Data_<Sp>::MatrixOp( BaseGDL*
 	dimension dim(NbCol2, NbRow2);
 
 	Data_* res = new Data_(dim, BaseGDL::NOZERO);
-	Map<Matrix<Ty,-1,-1>,Aligned> m2(&(*res)[0], NbCol2, NbRow2);
+	Map<Matrix<Ty,Dynamic,Dynamic>,Aligned> m2(&(*res)[0], NbCol2, NbRow2);
 	m2.noalias() = m0 * m1.transpose();
 	return res;
       } else if (at)
@@ -1591,7 +1591,7 @@ Data_<Sp>* Data_<Sp>::MatrixOp( BaseGDL*
 	dimension dim(NbCol2, NbRow2);
 
 	Data_* res = new Data_(dim, BaseGDL::NOZERO);
-	Map<Matrix<Ty,-1,-1>,Aligned> m2(&(*res)[0], NbCol2, NbRow2);
+	Map<Matrix<Ty,Dynamic,Dynamic>,Aligned> m2(&(*res)[0], NbCol2, NbRow2);
 	m2.noalias() = m0.transpose() * m1;
 	return res;
       } else
@@ -1606,7 +1606,7 @@ Data_<Sp>* Data_<Sp>::MatrixOp( BaseGDL*
 	dimension dim(NbCol2, NbRow2);
 
 	Data_* res = new Data_(dim, BaseGDL::NOZERO);
-	Map<Matrix<Ty,-1,-1>,Aligned> m2(&(*res)[0], NbCol2, NbRow2);
+	Map<Matrix<Ty,Dynamic,Dynamic>,Aligned> m2(&(*res)[0], NbCol2, NbRow2);
 	m2.noalias() = m0*m1;
 	return res;
       }