How to replace a value at a specif place in a matrix with another value?

I want to replace the value of the Matrix “q_update” (Size: (3, 1)) at position “a”, which can be a number between 1 and 3, with a new value. The new Value at this position should be y, a float32.
But unfortunaly it doesnt work. I Tried the following:

q_update[ a, 1] == y

but unfortunaly the values don’t change:

do you have any Idea how to do this properly?
Thanks a lot!

== is the comparison operator, not an assignment - you want = instead.

ok that was easy, thanks a lot!