vim script to insert ascii-art formulas

Question

I try to use Vim as much as I can to learn it.
Today I had to write lots of mathematical functions. I wrote them like f(x)=e^(x/sqrt(x)) (nonsensefunction for example) but this is very hard to read.

My idea was to use the console output of maxima and insert it in the text to get something like:

             x
          -------
          sqrt(x)
f(x) := e

which is very easy to read.

I already know a lot of maxima commands so it would be very easy and productive for me to write formulas in the maxima syntax and get them in this wonderful output :)

I had absolutely no experience with vimscript. How can I do this?

Answer 1

i use this in my ~/.vimrc file:

 " calls maxima --very-quit -r "[ARG];"
 function! AsciiMath(formula)
   let cmdln='maxima --very-quiet -r "'.a:formula.';"'
   let @a=system(cmdln)
   if !v:shell_error
 "    echo @a
     put a
   else
     echo '"'.a:formula.'" is an invalid maxima expression"'
   endif
 endfunction 

and call it like:
:call AsciiMath("f(x):=e^(x/sqrt(x))")

i think the function is straght forward to understand, but there are some tricky parts:

• put requires a register as argument see :h registers and :h put
• arguments cannot be used like formula they need the prefix (namespace) a: use it like a:formula.
• if you have vim configured to reload the .vimrc file then you should use function! instead of function because otherwise you 'll get an error (something like "[FUNCTIONNAME] is allready defined")
• system() returns the console output of its argument as returnvalue and puts the returnvalue of its argument in v:shell_error.

Answer 2

As long as you have an external command that returns the (rendered formula) output to stdout, the :read! {cmd} command will insert the output (below the current line or at the prepended [range]:

:read! maxima --very-quiet -r "formula"

You can make a custom command for this, too:

:command! -nargs=1 -range Maxima execute '<line1>,<line2>read! maxima --very-quiet -r' shellescape(<q-args>, 1)