I have vim-latex installed via Vundle and I'm trying to disable some annoying mapping that it sets up by default. From the docs I know that, for example, I can use the following command to unmap FEM:
call IUNMAP('FEM','tex')
But when I type that I get the error E117: Unknown function: IUNMAP.
I have installed vim-latex with Vundle by including Plugin 'LaTeX-Suite-aka-Vim-LaTeX' in my vimrc and I have just used the PluginUpdate command to update everything, which runs with no error, so I should have the latest version of the package.
Am I missing something here?
Actually, the problem you're having is related to where you're getting your vim-latex from.
With:
Plug 'LaTeX-Suite-aka-Vim-LaTeX'
You're getting it from here, which you'll notice hasn't been updated since 2010. Looking at the plugin/imaps.vim file in that repository, you'll see there's a definition for function IMAP(), but not for IUNMAP(), which was probably introduced after the last date that repository was synced...
Use this source instead:
Plug 'vim-latex/vim-latex'
Which will get it from here which is an official maintained location for this plug-in.
If you look at plugin/imaps.vim in that source tree, you'll notice function! IUNMAP is defined there.
Updating to the correct plug-in location should fix this problem for you (together with probably quite a few fixes from the last 10 years!)