TweetFollow Us on Twitter

Column TagJörg's Folder

Language Systems FORTRAN 3.3

Performance test & FORTRAN to C conversion

By Jörg Langowski, MacTech Magazine Regular Contributing Author

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

Since Absoft has just brought out a new Fortran compiler (see July column, MacFORTRAN 3.2), the competition wasn’t sleeping: as I told you in my last column, Language Systems has brought out version 3.3 of their Fortran. It’s now installed (I got it the day I sent off the last column) and here are the Benchmark figures. Note: All benchmark tests were run at optimization level 3 for the LS Fortran compiler and at level -O (i.e. basic optimizations but no loop unrolling and subroutine folding) for the Absoft compiler. First, the results of the Linpack program for LS Fortran 3.3:

Linpack performance, single precision

LSF 3.3 MacIIx 0.125 MFlops

Q700, 68030 code 1.33 MFlops

Q700, 68040 code 1.33 MFlops

These performances are exactly the same as for version 3.0.1. It is interesting that it makes no difference at all whether 68030 or 68040 code is generated; it seems that the Absoft compiler is still making better use of the 68040 specifics. For example, Absoft MacFortran v3.3 runs the same code at 1.30 MFlops on a Quadra 700 when 68030 code is generated (thus at the same speed as LS Fortran) and at 1.61 MFlops for native 68040 code, i.e. 25% faster.

Language Systems has added a faster transcendental function library for the 68040, however. Since the Linpack does not use transcendental functions, this feature is not tested. Another known program, the Savage benchmark, tests accuracy and speed of some built-in math functions (see listing). The results, comparing the latest versions of the LS and Absoft compilers:

Savage Benchmark (execution times and results)

LSF 3.3 MacIIx 3.60 s 2500.000

Q700, 68030 code 3.02 s 2500.000

Q700, 68040 code 1.80 s 2500.000

Absoft MacIIx 3.52 s 2499.886

extended precision 3.65 s 2500.000

Q700, 68030 code 3.23 s 2499.886

Q700, 68040 code 1.37 s 2477.244

Q700, double precision

68040 code 1.43 s 2500.000

One thing that is immediately evident is the shabby performance of the 68040 on 68030 code; the Quadra 700 is no faster here than a Mac IIx! But this comes as no surprise: the 68040 FPU has no transcendental functions and EXP, LOG, etc. must be emulated in software. The 68040 math libraries of both LS and Absoft Fortran are much faster than the Apple emulation. For Absoft on the 68040, you have to take care that you compile with the ‘double precision transcendentals’ option, on the 68040, or with the extended precision option on the 68030, otherwise precision really breaks down. On the 68030, two compilers have identical performance speed- and precision-wise on the Savage benchmark. On the 68040, Absoft again has the speed edge over LS Fortran by about 30%.

So it is fair to say that Absoft’s compiler still produces the fastest-running Fortran code for the 68040; however, when you port programs from other systems, you should be very careful in checking the numerical accuracy against known results. Or play it safe in any case by using default double or extended precision, which doesn’t slow down execution too much.

To save the honor of the Macintosh, one should say that on so-called ‘bigger’ systems you have similar problems: for instance, on a VAX or on a Silicon Graphics workstation you have to declare A double precision to get the correct answer of 2500.000.

It seems at the moment that the Fortran compilers for the Macintosh are at a stage where they have converged to their respective limits of performance, and both are very similar speed- and precision-wise except for Absoft’s higher speed on a 68040. On the other hand, LS Fortran is still the only compiler that creates code to run on systems without an FPU. I guess what one should expect next from Language Systems is that they work on their Macintosh interface, for instance it would be nice to have multiple output windows connected to Fortran units.

Fortran to C

For those of you who have inherited some thousand lines of Fortran code and want to port it to the Mac, there may still be another way to go than using one of those excellent Fortran compilers. Even though Fortran is much better than its reputation with some people (you just have to look at the code provided by Language Systems of Absoft for full Macintosh applications), you might prefer to put in the work of converting your whole program into C, or C++. It is true that you may can gain a lot in readability and maintainability this way; but that mountain of work rewriting the code

Well, if you want to give up your Fortran nostalgia and like the fast compile/test cycle that Think C offers (there is no Think Fortran), here is a program for you: f2c, a public domain Fortran-to-C translator that has been around on Unix systems for quite a while. Some time ago, Basil Duval from Switzerland took the time to convert this program to Think C and put the result into the public domain Info-Mac archives at Stanford. His README file explains what he did:

“IMPORTANT--- This file and the others are available via anonymous ftp on

f2c Conversion on the MAC

Basil P. Duval Jan 1992, EPFL/CRPP Bassenges 1015 Lausanne, Switzerland

(This software is submitted free of change and may not be sold)



This note describes a port of f2c to the THINK C Mac environment. The program f2c and the libraries libI77 and libF77 were converted and fortran programs have been successfully translated and linked to form working applications. In this first port, the default THINK C standard "Glass Window" screen is used to perform user input and output.

Version converted

The version taken from the server the 9 jan 1992 and has the 30 december 1991 time stamp.


The main problem with the port from UNIX to the Mac has been the 32k limit on global variables present up to version 5 of THINK C. Version 4 of THINK C allows string variables to be placed in a separate section. by simply requesting this option in the project options, the global variables were reduced from 56k to 31.6k which is acceptable in the Mac environment. Thus the program could be linked and tested. This enabled other problems of the port to surface. The main problem is due to the confusion with short and long integers. Up to THINK C 4, short was always defined as 2 bytes. In particular this causes several bugs when using the "strn..." functions which expect a (long) integer and as the code arrived were only given a 2 byte (short). The last problem was to provide a simple user interface. THINK C provides a console library which emulates the UNIX style command line via the "ccommand" routine which has been used to provide a rudimentary, but serviceable, interface. A list of the files that were changed is provided and the details of each change are provided at the end of this note.

(details omitted-JL)

Enclosed is a complete translation of the source using THINK C 5.02 together with a test file temp.f and a test project. The application has been compiled and linked for a Mac with 68030 and 68882 FPU unit but with the projects this could easily be changed. I spend the time since you mailed me getting the latest version of the f2c and putting in the bits needed to make it fly on the Mac, and so this version is labelled May 1992.

Good luck. The C source code is not supposed to be easy to edit, but it does get you quite a long way from the Fortran.

Basil Duval 2 June 1992

PS:Language Systems Fortran together with MPW 3.2 is a great combination if you decide to stay in fortran. THINK C is however a great environment for the Mac....”

The ready-to-use f2c application will be on the source code disk; for space reasons we cannot distribute the full system. If you have Internet access, you can however get the files via ftp either from the address given in the README file (see above), or from the Info-Mac archives at The conversion of the Savage benchmark is enclosed as an example in Listing 2. Of course you could have done this better by hand - however when you’re dealing with 4000 lines of code, that’s another story. I’ll try my hands on one of the big programs I have here until the next column and tell you my experiences - but first I have to get familiar with Think C, which I have never seriously used, believe it or not. Until then.

Listing 1: Savage Benchmark
CSECNDS is a real*4 function that returns 
Cseconds and fractional seconds.  The value is
Cmodified by subtracting the supplied argument.
CIt acts as in the VMS FORTRAN Manual.
 real*4 SECNDS
 real*4 time
 write(*,*) 'Starting '
 time = SECNDS(0.0)
 DO 200 J=1,10
 DO 100 I=1,2499
 time = SECNDS(time)
 WRITE (*,10) A
10 FORMAT(' A=',F17.12)
 write(*,*) time,' seconds'
 real time
 n = LONG(362)
 SECNDS = FLOAT(n)/60.0 - time
Listing 2: Savage Benchmark, converted to C by the f2c translator

/*  -- translated by f2c (version of 23 May 1992  14:18:33).
   You must link the resulting object file with the libraries:
 -lF77 -lI77 -lm -lc   (in that order)

#include "f2c.h"

/* Table of constant values */

static integer c__9 = 9;
static integer c__1 = 1;
static real c_b4 = (float)0.;
static integer c__4 = 4;

/* !MP inlines.f */
/* Main program */ MAIN__()
    /* Format strings */
    static char fmt_10[] = "(\002 A=\002,f17.12)";

    /* Builtin functions */
    integer s_wsle(), do_lio(), e_wsle();
    double sqrt(), log(), exp(), atan(), tan();
    integer s_wsfe(), do_fio(), e_wsfe();

    /* Local variables */
    static real time, a;
    static integer i, j;
    extern doublereal secnds_();

    /* Fortran I/O blocks */
    static cilist io___1 = { 0, 6, 0, 0, 0 };
    static cilist io___6 = { 0, 6, 0, fmt_10, 0 };
    static cilist io___7 = { 0, 6, 0, 0, 0 };

/* SECNDS is a real*4 function that returns */
/* seconds and fractional seconds.  The value is */
/* modified by subtracting the supplied argument. */
/* It acts as in the VMS FORTRAN Manual. */

    do_lio(&c__9, &c__1, "Starting\311", 9L);
    time = secnds_(&c_b4);
    for (j = 1; j <= 10; ++j) {
      a = (float)1.;
      for (i = 1; i <= 2499; ++i) {
        a = tan(atan(exp(log(sqrt(a * a))))) + (float)1.;
/* L100: */
/* L200: */
    time = secnds_(&time);
    do_fio(&c__1, (char *)&a, (ftnlen)sizeof(real));
    do_lio(&c__4, &c__1, (char *)&time, (ftnlen)sizeof(real));
    do_lio(&c__9, &c__1, " seconds", 8L);
} /* MAIN__ */


Community Search:
MacTech Search:

Software Updates via MacUpdate

Printopia 3.0.8 - Share Mac printers wit...
Run Printopia on your Mac to share its printers to any capable iPhone, iPad, or iPod Touch. Printopia will also add virtual printers, allowing you to save print-outs to your Mac and send to apps.... Read more
ForkLift 3.2.1 - Powerful file manager:...
ForkLift is a powerful file manager and ferociously fast FTP client clothed in a clean and versatile UI that offers the combination of absolute simplicity and raw power expected from a well-executed... Read more
BetterTouchTool 2.417 - Customize multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
Printopia 3.0.8 - Share Mac printers wit...
Run Printopia on your Mac to share its printers to any capable iPhone, iPad, or iPod Touch. Printopia will also add virtual printers, allowing you to save print-outs to your Mac and send to apps.... Read more
BetterTouchTool 2.417 - Customize multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
Mellel 4.1.0 - The word processor for sc...
Mellel is the leading word processor for OS X and has been widely considered the industry standard for long form documents since its inception. Mellel focuses on writers and scholars for technical... Read more
ScreenFlow 7.3 - Create screen recording...
ScreenFlow is powerful, easy-to-use screencasting software for the Mac. With ScreenFlow you can record the contents of your entire monitor while also capturing your video camera, microphone and your... Read more
Dashlane 5.9.0 - Password manager and se...
Dashlane is an award-winning service that revolutionizes the online experience by replacing the drudgery of everyday transactional processes with convenient, automated simplicity - in other words,... Read more
ForkLift 3.2 - Powerful file manager: FT...
ForkLift is a powerful file manager and ferociously fast FTP client clothed in a clean and versatile UI that offers the combination of absolute simplicity and raw power expected from a well-executed... Read more
Cocktail 11.5 - General maintenance and...
Cocktail is a general purpose utility for macOS that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more

Latest Forum Discussions

See All

Destiny meets its mobile match - Everyth...
Shadowgun Legends is the latest game in the Shadowgun series, and it's taking the franchise in some interesting new directions. Which is good news. The even better news is that it's coming out tomorrow, so if you didn't make it into the beta you... | Read more »
How PUBG, Fortnite, and the battle royal...
The history of the battle royale genre isn't a long one. While the nascent parts of the experience have existed ever since players first started killing one another online, it's really only in the past six years that the genre has coalesced into... | Read more »
Around the Empire: What have you missed...
Oh hi nice reader, and thanks for popping in to check out our weekly round-up of all the stuff that you might have missed across the Steel Media network. Yeah, that's right, it's a big ol' network. Obviously 148Apps is the best, but there are some... | Read more »
All the best games on sale for iPhone an...
It might not have been the greatest week for new releases on the App Store, but don't let that get you down, because there are some truly incredible games on sale for iPhone and iPad right now. Seriously, you could buy anything on this list and I... | Read more »
Everything You Need to Know About The Fo...
In just over a week, Epic Games has made a flurry of announcements. First, they revealed that Fortnite—their ultra-popular PUBG competitor—is coming to mobile. This was followed by brief sign-up period for interested beta testers before sending out... | Read more »
The best games that came out for iPhone...
It's not been the best week for games on the App Store. There are a few decent ones here and there, but nothing that's really going to make you throw down what you're doing and run to the nearest WiFi hotspot in order to download it. That's not to... | Read more »
Death Coming (Games)
Death Coming Device: iOS Universal Category: Games Price: $1.99, Version: (iTunes) Description: --- Background Story ---You Died. Pure and simple, but death was not the end. You have become an agent of Death: a... | Read more »
Hints, tips, and tricks for Empires and...
Empires and Puzzles is a slick match-stuff RPG that mixes in a bunch of city-building aspects to keep things fresh. And it's currently the Game of the Day over on the App Store. So, if you're picking it up for the first time today, we thought it'd... | Read more »
What You Need to Know About Sam Barlow’s...
Sam Barlow’s follow up to Her Story is #WarGames, an interactive video series that reimagines the 1983 film WarGames in a more present day context. It’s not exactly a game, but it’s definitely still interesting. Here are the top things you should... | Read more »
Pixel Plex Guide - How to Build Better T...
Pixel Plex is the latest city builder that has come to the App Store, and it takes a pretty different tact than the ones that came before it. Instead of being in charge of your own city by yourself, you have to work together with other players to... | Read more »

Price Scanner via

Back in stock! Apple’s full line of Certified...
Save $300-$300 on the purchase of a 2017 13″ MacBook Pro today with Certified Refurbished models at Apple. Apple’s refurbished prices are the lowest available for each model from any reseller. A... Read more
Back in stock: 13-inch 2.5GHz MacBook Pro (Ce...
Apple has Certified Refurbished 13″ 2.5GHz MacBook Pros (MD101LL/A) available for $829, or $270 off original MSRP. Apple’s one-year warranty is standard, and shipping is free: – 13″ 2.5GHz MacBook... Read more
Apple restocks Certified Refurbished 2017 13″...
Apple has Certified Refurbished 2017 13″ MacBook Airs available starting at $849. An Apple one-year warranty is included with each MacBook, and shipping is free: – 13″ 1.8GHz/8GB/128GB MacBook Air (... Read more
8-Core iMac Pro on sale for $4699, save $300
Amazon has the 8-core iMac Pro on sale for $4699 including free shipping. Their price is $300 off MSRP, and it’s the currently lowest price available for an iMac Pro. For the latest up-to-date prices... Read more
10″ 512GB WiFi iPad Pros on sale for $849, sa...
B&H Photo has Space Gray and Rose Gold 10.5″ 512GB WiFi iPad Pros on sale for $849. Their price is $150 off MSRP, and it’s the lowest price available for these models, new, from any Apple... Read more
MacBook Pro sale! B&H drops prices on new...
B&H Photo has dropped prices on new 2017 13″ MacBook Pros, with models now on sale for up to $200 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only. Their... Read more
13″ MacBook Airs on sale for $100-$150 off MS...
B&H Photo has 13″ MacBook Airs on sale for $100-$150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13″ 1.8GHz/128GB MacBook Air (MQD32LL/A): $899, $... Read more
Huge iMac sale! Apple reseller now offering 2...
B&H Photo has new 2017 21″ & 27″ iMacs on sale today for up to $300 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 27″ 3.8GHz iMac (MNED2LL/A): $... Read more
Sale! 1.4GHz Mac mini for $399, $100 off MSRP
B&H Photo has the 1.4GHz Mac mini on sale for $399 for a limited time. Their price is $100 off MSRP, and it’s the lowest price available for a mini from any Apple reseller: – 1.4GHz Mac mini (... Read more
Sale of the year continues as Apple resellers...
Adorama has new 2017 15″ MacBook Pros on sale for $250-$300 off MSRP. Shipping is free, and Adorama charges sales tax in NJ and NY only: – 15″ 2.8GHz Touch Bar MacBook Pro Space Gray (MPTR2LL/A): $... Read more

Jobs Board

*Apple* Genius - Technical Customer Service...
Job Description:Job SummaryAs a Genius at the Apple Store, you maintain customers' trust in Apple as the skilled technical customer service expert, Read more
Metadata Operations Specialist, *Apple* Med...
# Metadata Operations Specialist, Apple Media Products Job Number: 113387726 Santa Clara Valley, California, United States Posted: 08-Feb-2018 Weekly Hours: 40.00 Read more
*Apple* Retail - Multiple Positions - Apple,...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Data Scientist, *Apple* Ecosystem (AMP Anal...
# Data Scientist, Apple Ecosystem (AMP Analytics) Job Number: 113428728 Santa Clara Valley, California, United States Posted: 24-Jan-2018 Weekly Hours: 40.00 **Job Read more
*Apple* Professional Learning Specialist - A...
# Apple Professional Learning Specialist Job Number: 113456892 Englewood, NJ, New Jersey, United States Posted: 02-Feb-2018 Weekly Hours: 40.00 **Job Summary** The Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.