Using the Lahey Fortran Compiler with Source-Code GEMPACK

NOTE: Since GEMPACK Release 12.0 (September 2018) no version of the Lahey Fortran Compiler is supported. This page refers only to earlier releases of GEMPACK

Lahey Fortrans

Lahey currently sells several Fortran compilers for Windows PCs, but only one can be used with recent GEMPACK releases.

The relevant one is called LF Express [aka Lahey/Fujitsu Fortran], costing around $US250, details here. [Until recently this Lahey/Fujitsu compiler was called LF95. It is referred to as LF95 in the GEMPACK documentation and when you install GEMPACK.]
An LF Express single-user licence requires internet activation and can be installed on one PC only.
An older version is called LF90. You can use this with Releases 8.0 through 10.0 of GEMPACK, but we do not support it for GEMPACK Release 11 or later.
Since 2013 there is also Lahey/GNU Fortran for 32 and 64 bit Windows, which is NOT supported by GEMPACK. Lahey/GNU Fortran [aka LGF Shasta or LGF Lassen] is a customized version of GFortran. GEMPACK offers and supports our own free version of GFortran, details here.

See more details at http://www.lahey.com

Purchasing your compiler

Lahey sell their Fortran compiler through distributors and dealers, including leading Fortran vendor Polyhedron, or, in Australia, Devin Trussell of Computer Transition Systems.

Appropriate Versions of LF, LF90 and LF95

We are aware of no problems with version 7 or version 7.1 of LF.
We recommend version 5.70f of LF95. [We have found some problems with version 5.60. Programs compiled with version 5.60 may crash during LU decomposition if memory is tight. This does not happen with version 5.70.]
We only support version 4.50i of LF90 (and then only for GEMPACK release 10 and earlier).
The cut-down Lahey version, Essential Lahey Fortran 90 (ELF90), is not suitable for use with GEMPACK.

Get the latest Lahey maintenance update for your Fortran

You can download at no cost the latest Lahey maintenance update for your particular version of LF, LF95 or LF90. We recommend that you always work with the latest one available.

Type "lf95 -ver" at command line to find out which version you have.
If you have LF95 version 5.6 you must upgrade to latest version 5.6h.
If you have LF95 version 5.7 you should upgrade to latest version 5.7f.
More Lahey updates here.

Installing Lahey Fortran

Follow the default install procedure for your version of Lahey Fortran. Then perform the following test.

"Hello World" test for Lahey Fortran

You must test your installation of Lahey Fortran as follows. Right click and choose "Save Link As" or "Save Target As" depending on your browser, to save the small program hello.for into a temporary folder, say C:\test. When compiled and executed this program will write "Hello World" to the terminal. Next, open a command prompt in the C:\test folder (containing hello.for). Then type the following commands.

C:\test>lf95 hello.for
C:\test>hello

[For LF90, type "lf90 hello.for" for the first command.] The first command produces the executable program hello.exe.The second command, "hello", runs the hello.exe program which will write the words "Hello World" to the terminal. If you see "Hello World" then your compiler installation is working.

Problems installing older LF95 versions on 64-bit Windows

The installer program for older LF95 versions [LF95 5.60 or 5.70] uses 16-bit components which will not run under 64-bit Windows. However you can simply copy LF95 from another PC where it did install successfully. Print out and follow these instructions.

F77L3 (Lahey Fortran 77, F77L3/EM-32)

This can only be used with Release 7.0 or earlier of GEMPACK.
This does not run under Windows XP, Windows 7 or later Windows versions.
We recommend that users of F77L3 upgrade to LF Express, or (for GEMPACK 10 and later) the Intel compiler, or (for GEMPACK 11 and later) the free GFortran compiler.

Sharing Header Array Files with Other GEMPACK Users

The binary files (including Header Array files) produced by the older compilers LF90 or F77L3 are not completely compatible with those produced using the modern Intel or LF and LF95 compilers. However GEMPACK programs convert between the old and new styles without any user intervention.

FLIB_DVT_BUFFER environment variable

EXE files produced by the Lahey LF or LF95 compiler tend to use memory wastefully. Probably you would only notice this when running a very large model. The problem is fixed by creating and setting the Environment variable FLIB_DVT_BUFFER equal to 0 (ie, zero). The EXE file does not need to be recompiled.

Install packages for GEMPACK Release 10 and later automatically set FLIB_DVT_BUFFER=0, even if you chose the Intel compiler. The reason is, you may wish to run a model EXE from another source, such as a RunGTAP package. If that EXE was made by LF or LF95, its performance on your PC might be improved by the FLIB_DVT_BUFFER setting.