Fortran Logo Refined

Fortran Logo Refined
The “F” logo designed by Jacobs William (@jacobwilliams) and Milan Curcic (@milancurcic) is based on the F letter shown on the cover of the original IBM Fortran programmer’s reference manual in 1956. The idea is brilliant, but the logo uses Clarendon BT font, which, if you look carefully, is not the font used by the original reference manual. Therefore, I did some research and figured out a method to parameterize the “F” letter. Since this is a logo refinement for the Fortran programming language, naturally we want to do everything with Fortran:)

Github repo if you are interested:
Fortran Logo Refined


:wave: :wave:

Beautiful, brilliant, thank you!

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Looks great–let’s use it!

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Thank you!

Hi, Milan
Thank you! Is there anything I need to do on my side (for example, publish a release)?

“Jacob Williams”, not “Jacobs William”. :slight_smile:

Why do you say the font is not Clarendon? I used this WhatTheFont page to identity the font from an upload of the original manual image. It identified the font as Clarendon. If you overlay my original svg with the image from the original manual, you will see they are identical.

The font in your version does not quite have the same proportions as the one in the original Fortran manual…

(left: manual overlaid on the current logo. right: manual overlaid on yours)


Hi, Jacob
Apologies for spelling your name wrong. Won’t happen again!

I would like to argue that manually overlay screenshots is probably not the best way to compare these icons, especially when the original “F” is not a print version but a very small area of a scanned book cover. This makes it nearly impossible to create an identical shape as the original “F”.

The way I compare it is to:

  1. Crop the “F” letter by its bottom left and upper right corners, which happens to be two right-angle corners. Now we have a rectangular shaped image.
  2. Map the rectangular shaped image to a square.
  3. Compare the mapped squares.

The result is shown below.

(The first row: original “F”, the second row: current icon, orange line: parameterized version)

As you see, the major difference between the current icon (Clarendon) and the original “F” lies among all the curving parts. This is especially conspicuous when you compare the “Corkscrew” part of the two letters, where the original “F” has a constant-width “arm”, but the current icon has a gradually widened “arm”. This is the reason that I think the original “F” is not Clarendon, or the Clarendon chosen in the current icon design.

Why? Can’t it be rectangular? That seems to be the main difference in Jacob’s comparison (your font seems to match closely the logo of the book in one stretches a little bit it).


You are correct. The shape of the letter “F” does not have to be rectangular, in fact it’s width to height ratio is 23/25. However, when comparing the original and current version of the letter “F”, mapping them to a square makes it easier to compare. The main difference between the two is that the circled portion of the original “F” and the current “F” are not the same, and this is not due to stretching the image. The difference is caused by using different combinations of curves, where the current “F” uses only one quadratic Bezier curve while the original “F” uses two straight lines and a quadratic Bezier curve. This makes the two "F"s appear very different.

(Left: Curve of the current “F”, Right: Curve of the original “F”)

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The Clarendon font was and is sold by various companies, since its first release in 1845. These typefaces are not identical. Thatʼs the reason why modern (digital) variants differ from the typefaces available in the 1950s, of which one was used for the book cover.

I see. I agree that your version fixes that curve on the F. But I don´t get the stretching thing. I think you would be more convincing with a better overlap with the original font (which you have, if the F is not artificially squared).

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I can’t distinguish the two logos. I assume that most people can’t either.

I think it’s pointless to debate about whether one logo more exactly represents the original letter F from the manual, or whether one or the other better resembles Clarendon.

We were inspired by the original F based on its classic aesthetic and it being on the Fortran manual, but exactly reproducing it is not necessary.

But consider these two stories:

  1. The Fortran logo is the capital letter F using the Clarendon font;
  2. The Fortran logo is programmatically generated using Fortran.

I think 2 is a better story. It’s great to have an fpm package that allows us to generate the logo, or make variations to it.



That’s exactly what is brilliant and beautiful with the effort by @han190 . It is also great to see how the Fortran code is parameterized by @han190. It also hints at what is possible with Fortran, it reinforces my belief the computing domains really, really need to rediscover Fortran.


Since a logo is square, why not make the F square too? :slight_smile:

I’m not totally following the reasoning for the changes. I think the F was stretched a little bit? It doesn’t look closer to the original manual F to me. I still like the current one better…

left to right: original manual, current, proposed.

The main issue is the proposed new logo is no longer a square. When I open the proposed new svg in Inkscape the purple box is 211.85 x 223.210. I think it would be better to keep it a square.

Also, when I remove the color, I’m seeing some rogue lines in the new svg:

Not sure why those are there.

The original svg is very clean and only 5 kb. Sure, we could extract the curve from the svg and write it from Fortran, but I don’t really find that very compelling. The proposed new one is 47 kb and seemingly very complicated.

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  1. I altered the aspect ratio of the logo from square to 23/25, taking into account the original “F” logo and feedback suggesting a return to the original ratio. To me they look (almost) identical

I can easily revert it back to square by adjusting the parameters in the parameters.nml. Perhaps offering a command line option for “original ratio” and “square” would be a better idea.
2. The svg file appears messy because it is challenging for gnuplot to fill an area with empty holes. To fill a connected area, a single closed curve must be created, thus the connected line.

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I understand the motivation was to have the F closer that of the original manual. I personally like that motivation. I don’t have strong feelings about that, really, just think that logo refinement should stick with its original motivation. I have the impression that both goals can be achieved here, since the logo as it is now is not exactly an exact reproduction of the original manual F, so probably both things can be combined enough.

edit: now the figure above seems to be perfect, isn’t it?

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At least I’m happy with it. This was supposed to be a Lunar-New-Year-killing-time project, definitely not expecting lively discussions like this :slight_smile: , now I have a lot more to update for this project :rofl:


I was impressed by the length of the Clarendon typeface Wikipedia page:

It says for example:

Clarendon fonts proved extremely popular in many parts of the world, in particular for display applications such as posters printed with wood type. They are therefore commonly associated with wanted posters and the American Old West.

@han190, you could make a Wanted poster:
born in 1957
crushing numbers faster than light


Dead or alive
Born in 1957
Crunching numbers faster than light
Found nowhere and everywhere all at once


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