Lambda Example: Generate Fibonacci series

davidleal  so I did not read up on any of this but do have 2 questions:

a) Why are you using a [2x2] * [2x2] instead of [1x2] * [2x2] ?  Basically aren't you using the matrix multiplication to hold your prior value so [a b] * [ 1,1; 1,0] => [a+b,  a] and you don't need the second row?

b) Why are you then using INDEX( .... ,2, 1) which is essentially the value 1 calculation behind instead of SEQUENCE(n-2) and INDEX(... 1,1) or in my suggestion just INDEX(..., 1)

I don't see any time performance improvements using my crude timer but it just makes sense to me:

FIBO_MAT=LAMBDA(n, LET(a, {1,1;1,0}, 
    IF(n>2,
       INDEX(REDUCE({1,1},SEQUENCE(n-2),
         LAMBDA(ac,_,MMULT(ac,a))),1),
       1)))