Change font size in context by percentage

Question

Font sizes can be set with (more or less) absolute commands such as \large, \Large, \LARGE, and so on.

Are there also commands that can increase or reduce a font size by some proportion or percentage not in absolute terms but relative to the preceding text?

I am hoping to find a way to do this in the midst of chapter titles, which are set in the preamble to be \LARGE\bfseries. But when a colon appears in a chapter title, followed by a subtitle, I am being asked to reduce the size of the subtitle by just a small amount — and the result of using the absolute \Large is not satisfactory. I could redefine \Large just for this situation, but I'd prefer to find a relative command to change font size, as described above, as that would be useful in many other situations.

Answer 1

Thanks to the hint from Brent.Longborough, I found the relsize package, which does what is required.

The package allows relative resizing of fonts: normally, resizing is done to the ten fixed "sizing commands" (\Large etc.). To go to the next whole size up one uses \larger or \relsize{1}, to the next whole size down \smaller or \relsize{-1}.

The interesting thing is that fine control of this kind can be attained with the commands \relscale{〈factor〉} and \text-scale{〈factor〉}{〈text〉}, where 〈factor〉 can be a non-integer decimal number.

In addition, \relsize also accepts a non-integer factor as argument: \relsize{0.8} (not mentioned in the 20030704 documentation).

Examples below, all showing a \LARGE chapter title with the font reduced after the colon:

• Font reduced using \Large{〈text〉} or \smaller or \relsize{-1}:

• Font reduced using \relscale{0.9}:

• Font reduced using \relsize{-0.8}: