add INSTALL

INSTALL

@@ -0,0 +1,18 @@
+
+There are three ways to use AMReX.
+
+(1) Use AMReX's GNU Make build system.  There is no installation step
+    in this approach.  Application codes are compiled together with
+    AMReX codes.  Most of the examples in Tutorials can be built this
+    way.  See `Tools/GNUMake/README.md` for more details.
+
+(2) Build and install static library libamrex.a, AMReX headers and
+    Fortran modules via `./configure` followed by `make` and `make
+    install`.  Type `./configure -h` to show help message.  An
+    application code uses its build system to compile and link to the
+    AMReX library.  See `Tutorials/libamrex_C` for an example.  Note
+    that this approach relies the make system in `Tools/GNUMake/`.
+    See `Tools/GNUMake/README.md` for more details on the make system.
+
+(3) CMake.
+

Tools/libamrex/configure.py

@@ -13,7 +13,7 @@ def configure(argv):
     argv[0] = "configure" # So the help message print it
     parser = argparse.ArgumentParser()
     parser.add_argument("--prefix",
-                        help="Install libarmex, headers and modules in PREFIX directory [default=tmp_install_dir]",
+                        help="Install libarmex, headers and Fortran modules in PREFIX directory [default=tmp_install_dir]",
                         default="tmp_install_dir")
     parser.add_argument("--dim", 
                         help="Dimension [default=3]",