Need help using math in markup command definition, and a feature request.

[dfro]

Fellow music engravers,

I have a feature request. Perhaps, this has been discussed already.

Sometimes, I would like the spacial formatting in a \markup command to 
respond to changes in fontsize, so that all of the \markup spacing will 
change proportional to the change in fontsize. I think having \markup 
formatting commands - like \fs-raise, \fs-lower, \fs-hspace, \fs-vspace, 
etc. - that respond to changes in \fontsize would be helpful. I am 
trying to make a basic define-markup-command function for \raise that 
would do this for whole number fontsizes, but I do not know how to add 
math to markup command definitions. Here is my non-working code sketch, 
so far.


<code start>

\version "2.24.1"

%global font-size variable
font-size =
#0
%#1

%fs-raise definition
#(define-markup-command (fs-raise layout props rs text1) (number? markup?)
   (interpret-markup layout props
                     (cond

                      ((equal? font-size 0)
                       ; I want to create variable r = rs * 1, like 
this, which does not work, #(define r (* 1 rs))

                       #{ \markup \fontsize #font-size \raise #r #text1 #}
                       )

                      ((equal? font-size 1)
                       ; I want to create variable r = rs * 1.25, like 
this, which does not work, #(define r (* 1.25 rs))

                       #{ \markup \fontsize #font-size \raise #r #text1 #}
                       )

                      ; more font-size conditionals go here.

                      (else #{ \markup \null #})
                      )
                     )
   )

%music block
{ c'1^\markup \fs-raise #1 "text" }


<code end>


My basic question is, how do you create a variable and do math on it 
inside a conditional statement within a define-markup-command function?


Peace,

David