diff -rupN gmsh-4.2.1-source/contrib/lbfgs/alglibinternal.cpp gmsh-4.2.1-source-new/contrib/lbfgs/alglibinternal.cpp
--- gmsh-4.2.1-source/contrib/lbfgs/alglibinternal.cpp	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/alglibinternal.cpp	2019-03-07 21:27:55.174342831 +0100
@@ -16,8 +16,8 @@ A copy of the GNU General Public License
 http://www.fsf.org/licensing/licenses
 >>> END OF LICENSE >>>
 *************************************************************************/
-#include "stdafx.h"
-#include "alglibinternal.h"
+#include <alglib/stdafx.h>
+#include <alglib/alglibinternal.h>
 
 // disable some irrelevant warnings
 #if (AE_COMPILER==AE_MSVC)
diff -rupN gmsh-4.2.1-source/contrib/lbfgs/alglibinternal.h gmsh-4.2.1-source-new/contrib/lbfgs/alglibinternal.h
--- gmsh-4.2.1-source/contrib/lbfgs/alglibinternal.h	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/alglibinternal.h	2019-03-07 21:27:55.175342737 +0100
@@ -18,7 +18,7 @@ http://www.fsf.org/licensing/licenses
 *************************************************************************/
 #ifndef _alglibinternal_pkg_h
 #define _alglibinternal_pkg_h
-#include "ap.h"
+#include <alglib/ap.h>
 
 
 /////////////////////////////////////////////////////////////////////////
diff -rupN gmsh-4.2.1-source/contrib/lbfgs/alglibmisc.cpp gmsh-4.2.1-source-new/contrib/lbfgs/alglibmisc.cpp
--- gmsh-4.2.1-source/contrib/lbfgs/alglibmisc.cpp	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/alglibmisc.cpp	2019-03-07 21:27:55.175342737 +0100
@@ -16,8 +16,8 @@ A copy of the GNU General Public License
 http://www.fsf.org/licensing/licenses
 >>> END OF LICENSE >>>
 *************************************************************************/
-#include "stdafx.h"
-#include "alglibmisc.h"
+#include <alglib/stdafx.h>
+#include <alglib/alglibmisc.h>
 
 // disable some irrelevant warnings
 #if (AE_COMPILER==AE_MSVC)
diff -rupN gmsh-4.2.1-source/contrib/lbfgs/alglibmisc.h gmsh-4.2.1-source-new/contrib/lbfgs/alglibmisc.h
--- gmsh-4.2.1-source/contrib/lbfgs/alglibmisc.h	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/alglibmisc.h	2019-03-07 21:27:55.176342643 +0100
@@ -18,8 +18,8 @@ http://www.fsf.org/licensing/licenses
 *************************************************************************/
 #ifndef _alglibmisc_pkg_h
 #define _alglibmisc_pkg_h
-#include "ap.h"
-#include "alglibinternal.h"
+#include <alglib/ap.h>
+#include <alglib/alglibinternal.h>
 
 /////////////////////////////////////////////////////////////////////////
 //
diff -rupN gmsh-4.2.1-source/contrib/lbfgs/ap.cpp gmsh-4.2.1-source-new/contrib/lbfgs/ap.cpp
--- gmsh-4.2.1-source/contrib/lbfgs/ap.cpp	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/ap.cpp	2019-03-07 21:27:55.177342549 +0100
@@ -16,8 +16,8 @@ A copy of the GNU General Public License
 http://www.fsf.org/licensing/licenses
 >>> END OF LICENSE >>>
 *************************************************************************/
-#include "stdafx.h"
-#include "ap.h"
+#include <alglib/stdafx.h>
+#include <alglib/ap.h>
 #include <limits>
 #include <locale.h>
 using namespace std;
diff -rupN gmsh-4.2.1-source/contrib/lbfgs/linalg.cpp gmsh-4.2.1-source-new/contrib/lbfgs/linalg.cpp
--- gmsh-4.2.1-source/contrib/lbfgs/linalg.cpp	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/linalg.cpp	2019-03-07 21:27:55.182342079 +0100
@@ -16,8 +16,8 @@ A copy of the GNU General Public License
 http://www.fsf.org/licensing/licenses
 >>> END OF LICENSE >>>
 *************************************************************************/
-#include "stdafx.h"
-#include "linalg.h"
+#include <alglib/stdafx.h>
+#include <alglib/linalg.h>
 
 // disable some irrelevant warnings
 #if (AE_COMPILER==AE_MSVC)
diff -rupN gmsh-4.2.1-source/contrib/lbfgs/linalg.h gmsh-4.2.1-source-new/contrib/lbfgs/linalg.h
--- gmsh-4.2.1-source/contrib/lbfgs/linalg.h	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/linalg.h	2019-03-07 21:27:55.183341985 +0100
@@ -18,9 +18,9 @@ http://www.fsf.org/licensing/licenses
 *************************************************************************/
 #ifndef _linalg_pkg_h
 #define _linalg_pkg_h
-#include "ap.h"
-#include "alglibinternal.h"
-#include "alglibmisc.h"
+#include <alglib/ap.h>
+#include <alglib/alglibinternal.h>
+#include <alglib/alglibmisc.h>
 
 /////////////////////////////////////////////////////////////////////////
 //
diff -rupN gmsh-4.2.1-source/contrib/lbfgs/optimization.cpp gmsh-4.2.1-source-new/contrib/lbfgs/optimization.cpp
--- gmsh-4.2.1-source/contrib/lbfgs/optimization.cpp	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/optimization.cpp	2019-03-07 21:27:55.186341703 +0100
@@ -16,8 +16,8 @@ A copy of the GNU General Public License
 http://www.fsf.org/licensing/licenses
 >>> END OF LICENSE >>>
 *************************************************************************/
-#include "stdafx.h"
-#include "optimization.h"
+#include <alglib/stdafx.h>
+#include <alglib/optimization.h>
 
 // disable some irrelevant warnings
 #if (AE_COMPILER==AE_MSVC)
diff -rupN gmsh-4.2.1-source/contrib/lbfgs/optimization.h gmsh-4.2.1-source-new/contrib/lbfgs/optimization.h
--- gmsh-4.2.1-source/contrib/lbfgs/optimization.h	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/optimization.h	2019-03-07 21:27:55.187341609 +0100
@@ -18,11 +18,11 @@ http://www.fsf.org/licensing/licenses
 *************************************************************************/
 #ifndef _optimization_pkg_h
 #define _optimization_pkg_h
-#include "ap.h"
-#include "alglibinternal.h"
-#include "alglibmisc.h"
-#include "linalg.h"
-#include "solvers.h"
+#include <alglib/ap.h>
+#include <alglib/alglibinternal.h>
+#include <alglib/alglibmisc.h>
+#include <alglib/linalg.h>
+#include <alglib/solvers.h>
 
 /////////////////////////////////////////////////////////////////////////
 //
diff -rupN gmsh-4.2.1-source/contrib/lbfgs/solvers.cpp gmsh-4.2.1-source-new/contrib/lbfgs/solvers.cpp
--- gmsh-4.2.1-source/contrib/lbfgs/solvers.cpp	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/solvers.cpp	2019-03-07 21:27:55.188341515 +0100
@@ -16,8 +16,8 @@ A copy of the GNU General Public License
 http://www.fsf.org/licensing/licenses
 >>> END OF LICENSE >>>
 *************************************************************************/
-#include "stdafx.h"
-#include "solvers.h"
+#include <alglib/stdafx.h>
+#include <alglib/solvers.h>
 
 // disable some irrelevant warnings
 #if (AE_COMPILER==AE_MSVC)
diff -rupN gmsh-4.2.1-source/contrib/lbfgs/solvers.h gmsh-4.2.1-source-new/contrib/lbfgs/solvers.h
--- gmsh-4.2.1-source/contrib/lbfgs/solvers.h	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/lbfgs/solvers.h	2019-03-07 21:27:55.188341515 +0100
@@ -18,10 +18,10 @@ http://www.fsf.org/licensing/licenses
 *************************************************************************/
 #ifndef _solvers_pkg_h
 #define _solvers_pkg_h
-#include "ap.h"
-#include "alglibinternal.h"
-#include "linalg.h"
-#include "alglibmisc.h"
+#include <alglib/ap.h>
+#include <alglib/alglibinternal.h>
+#include <alglib/linalg.h>
+#include <alglib/alglibmisc.h>
 
 /////////////////////////////////////////////////////////////////////////
 //
diff -rupN gmsh-4.2.1-source/contrib/MeshOptimizer/MeshOpt.cpp gmsh-4.2.1-source-new/contrib/MeshOptimizer/MeshOpt.cpp
--- gmsh-4.2.1-source/contrib/MeshOptimizer/MeshOpt.cpp	2019-02-16 10:18:07.000000000 +0100
+++ gmsh-4.2.1-source-new/contrib/MeshOptimizer/MeshOpt.cpp	2019-03-07 21:27:55.188341515 +0100
@@ -36,11 +36,11 @@
 
 #if defined(HAVE_BFGS)
 
-#include "ap.h"
-#include "alglibinternal.h"
-#include "alglibmisc.h"
-#include "linalg.h"
-#include "optimization.h"
+#include <alglib/ap.h>
+#include <alglib/alglibinternal.h>
+#include <alglib/alglibmisc.h>
+#include <alglib/linalg.h>
+#include <alglib/optimization.h>
 
 namespace {
 
diff -rupN gmsh-4.2.1-source/contrib/MeshOptimizer/MeshOpt.h gmsh-4.2.1-source-new/contrib/MeshOptimizer/MeshOpt.h
--- gmsh-4.2.1-source/contrib/MeshOptimizer/MeshOpt.h	2019-02-24 11:49:47.000000000 +0100
+++ gmsh-4.2.1-source-new/contrib/MeshOptimizer/MeshOpt.h	2019-03-07 21:27:55.189341421 +0100
@@ -39,7 +39,7 @@
 
 #if defined(HAVE_BFGS)
 
-#include "ap.h"
+#include <alglib/ap.h>
 
 class MeshOptParameters;
 
diff -rupN gmsh-4.2.1-source/contrib/MeshOptimizer/ObjContrib.h gmsh-4.2.1-source-new/contrib/MeshOptimizer/ObjContrib.h
--- gmsh-4.2.1-source/contrib/MeshOptimizer/ObjContrib.h	2019-02-24 11:49:47.000000000 +0100
+++ gmsh-4.2.1-source-new/contrib/MeshOptimizer/ObjContrib.h	2019-03-07 21:27:55.189341421 +0100
@@ -26,7 +26,7 @@
 #define OBJ_CONTRIB_H
 
 #include <string>
-#include "ap.h"
+#include <alglib/ap.h>
 #include "MeshOptCommon.h"
 
 class Patch;
diff -rupN gmsh-4.2.1-source/contrib/MeshOptimizer/ObjectiveFunction.h gmsh-4.2.1-source-new/contrib/MeshOptimizer/ObjectiveFunction.h
--- gmsh-4.2.1-source/contrib/MeshOptimizer/ObjectiveFunction.h	2019-02-24 11:49:47.000000000 +0100
+++ gmsh-4.2.1-source-new/contrib/MeshOptimizer/ObjectiveFunction.h	2019-03-07 21:27:55.189341421 +0100
@@ -27,7 +27,7 @@
 
 #include <string>
 #include <vector>
-#include "ap.h"
+#include <alglib/ap.h>
 
 class ObjContrib;
 class Patch;
diff -rupN gmsh-4.2.1-source/contrib/Revoropt/include/Revoropt/Solver/alglib_cg.hpp gmsh-4.2.1-source-new/contrib/Revoropt/include/Revoropt/Solver/alglib_cg.hpp
--- gmsh-4.2.1-source/contrib/Revoropt/include/Revoropt/Solver/alglib_cg.hpp	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/Revoropt/include/Revoropt/Solver/alglib_cg.hpp	2019-03-07 21:27:55.189341421 +0100
@@ -11,7 +11,7 @@
 #ifndef _REVOROPT_SOLVER_ALGLIB_CG_WRAPPER_H_
 #define _REVOROPT_SOLVER_ALGLIB_CG_WRAPPER_H_
 
-#include <libalglib/optimization.h>
+#include <alglib/optimization.h>
 
 namespace Revoropt {
 namespace Solver {
diff -rupN gmsh-4.2.1-source/contrib/Revoropt/include/Revoropt/Solver/alglib_lbfgs.hpp gmsh-4.2.1-source-new/contrib/Revoropt/include/Revoropt/Solver/alglib_lbfgs.hpp
--- gmsh-4.2.1-source/contrib/Revoropt/include/Revoropt/Solver/alglib_lbfgs.hpp	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/Revoropt/include/Revoropt/Solver/alglib_lbfgs.hpp	2019-03-07 21:27:55.189341421 +0100
@@ -11,8 +11,7 @@
 #ifndef _REVOROPT_SOLVER_ALGLIB_LBFGS_WRAPPER_HPP_
 #define _REVOROPT_SOLVER_ALGLIB_LBFGS_WRAPPER_HPP_
 
-//#include <libalglib/optimization.h>
-#include <optimization.h>
+#include <alglib/optimization.h>
 
 namespace Revoropt {
 namespace Solver {
diff -rupN gmsh-4.2.1-source/contrib/zipper/example.cpp gmsh-4.2.1-source-new/contrib/zipper/example.cpp
--- gmsh-4.2.1-source/contrib/zipper/example.cpp	2017-10-03 22:01:52.000000000 +0200
+++ gmsh-4.2.1-source-new/contrib/zipper/example.cpp	2019-03-07 21:27:55.190341327 +0100
@@ -1,7 +1,7 @@
 // ZipExample.cpp : Defines the entry point for the console application.
 //
 
-#include "stdafx.h"
+#include <alglib/stdafx.h>
 #include "zipper.h"
 #include "unzipper.h"
 #include <fstream>
diff -rupN gmsh-4.2.1-source/Geo/GFace.cpp gmsh-4.2.1-source-new/Geo/GFace.cpp
--- gmsh-4.2.1-source/Geo/GFace.cpp	2019-03-04 18:10:27.000000000 +0100
+++ gmsh-4.2.1-source-new/Geo/GFace.cpp	2019-03-07 21:27:55.190341327 +0100
@@ -27,8 +27,8 @@
 #endif
 
 #if defined(HAVE_BFGS)
-#include "stdafx.h"
-#include "optimization.h"
+#include <alglib/stdafx.h>
+#include <alglib/optimization.h>
 #endif
 
 // TODO C++11 remove macro