Shift interval from matrixctrl -> zl compare indexes
I have this simple system been using for some time
Using matrixctrl to choose set of notes
But only can shift (transpose) entire set
I would like to combine or add the output of matrixcntrl /zl compare with sliders to shift octave of each individual note selected
like this - how to get the indexes for zl compare - including zeros - to maintain position and do addition?

zl.compare does not output indexes if list matches.
at least in max 8 it is so.
means when you set all matrix cells to zero, last seen index will hang.
do I see that correctly ?
you set 13 notes using multislider, then activate its index for transposing in vexpr.
and de-transpose deactivated indexes ?
why not multiply transposition list using matrix row ?
if index 3 is 1 it will set transposition * 1, if it iz zero then no transposition
If I'm understanding you correctly (no guarantees!), maybe something like this will work? It's a basic sketch of something I worked out for one of my patches.
Thanks DEQUALSRXT - will look at your solution
I think I figured it out!
like this - x X (1+12/x) - 12 can be 24, 36 etc

I can just @replace " " the zeros and put in coll - transpose to whatever.
Not 100% sure if that's what you want, but:
Using -999 as an "unselected" indicator, and removing every item matching that value.
EDIT: didn't saw every other answers!
TFL - Its Max- all answers are golden!
Yeah I was working on that formula at same time.
Yours precisely recreates what I asked for.
Mine requires more steps to get to the coll.
I opted for not using zl compare and using output matrixctrl - starting at 1 (with list to 13) instead of 0-12 - to get to 0.
In the end they are just midi notes. So my fundamental sits around 21 A0
//
means when you set all matrix cells to zero, last seen index will hang.do I see that correctly ?yes. the patch you helped with a long time ago does that. but I never have 'synth on' with out at least one pitch selected