# Are there two different versions of the \mathcal{F} character?

I've seen two different versions of the \mathcal{F} character:

Version 1 (see the \mathcal{F}):

Version 2:

Notice that the top horizontal line of the F curves down on the left much more in version 1 than it does in version 2.

Which of these is the preferred \mathcal{F}? I know that some of the calligraphic capital letters were improved at one point, but I don't know which version is the improved one.

UPDATE OF 8/2/2017: Just today I did the automatic update of my MiKTeX---I am currently using pdfLaTeX, pdfTeX Version 3.14159265-2.6-1.40.18 (MiKTeX 2.9.6400), and TeXworks Version 0.6.2---and my \mathcal{F} has gone back to the old one. No other characters in any fonts seem to have changed. However, if I add the lmodern package, I can get the new \mathcal{F} in both regular and bold forms. Did something happen with the current version of MiKTeX?

• Hi MSC, please note that you can include images using one of icons on top of the edit box. You have now enough reputation points to do this. Feb 16, 2011 at 23:19
• the link for the first version of the example has gone dead. would it be possible to recreate the example, and add it via the recommended image upload? Aug 27, 2015 at 12:44
• Can you provide the correct image for version 1?
– Werner
Aug 2, 2017 at 17:44
• Okay, I found an image that should show the "old" \mathcal{F}. Sorry it's a little fuzzy.
– MSC
Aug 2, 2017 at 20:47

The final version of Computer Modern's mathcal F is the second one. To see it, you can compile with metafont the file cmsy10.mf (located in [texmf]/fonts/source/public/cm/; be sure you have the latest version). Here is the result, after conversion in dvi format with gftodvi:

If you compare the type 1 versions of Computer Modern, you see that the Bluesky/AMS and Latin Modern versions both have the right version. However, old versions of Latin Modern have the wrong mathcal F:

This means that if you use a recent TeX distribution, you should always have the final version ofthe mathcal F.

As an aside, my version of Computer Modern Typefaces, although recent, still shows the old version:

• Thank you. Is there also a new-style bold \mathcal{F}? My system uses the new-style normal \mathcal{F} but the old-style bold \mathcal{F}. I've noticed this discrepancy in a few other PDFs I've found on the web, too.
– MSC
Mar 10, 2011 at 17:40
• @MSC: yes, the bold also has a new version, but it's not in the Bluesky/AMS fonts. You can find it in the latest version of Latin Modern. So if your TeX distribution is recent, using \usepackage{lmodern} will ensure you're using the latest versions. Mar 10, 2011 at 20:24

If you include the command \usepackage{eucal}, then \mathcal{F} will produce the curlier one and \CMcal{F} will produce the other. It's up to you to decide which you prefer.

To more directly answer your question: Including the command \usepackage{eucal} changes the \mathcal command so that it will produce the curlier one; omitting that package will make \mathcal produce the less curly one.

• It is not possible to use the eucal package to switch between the two versions show by MSC. Both of MSC's examples come from the Computer Modern font whereas eucal uses the Euler font, which is completely different (the most visible difference being that it is upright instead of slanted). Feb 17, 2011 at 12:13
• Oops! I guess I should have looked more closely at those "F"s. Feb 18, 2011 at 1:17