Forum Discussion

Viz's avatar
Viz
Brass Contributor
Jan 05, 2021

Lambda Example: Generate Fibonacci series

In this post, I would like to explain how I have used Lambda to create a function to generate a Fibonacci series array.   This example can also be used to understand how to create an array where th...
excel
office 365
Patrick2788's avatar
Patrick2788
Silver Contributor
Apr 24, 2023

I realize this solution is not the most efficient but it was fun to create and it's a bit different (Inspired by Pascal's Triangle).

 

 

'DiagonalSum
=LAMBDA(a,v,VSTACK(
    a,
    IF(v < 3, 1, SUM(IFERROR(COMBIN(SEQUENCE(v - 1, , v - 1, -1), SEQUENCE(v - 1, , 0)), 0)))
))

'Fib
=LAMBDA(elements,REDUCE(0, SEQUENCE(elements), DiagonalSum))

 

PeterBartholomew1's avatar
PeterBartholomew1
Silver Contributor
Apr 24, 2023

Patrick2788 

I think I am becoming conditioned!  I only have to read the words Pascal's triangle and I find myself writing

=REDUCE(1, SEQUENCE(n),
    LAMBDA(triangle, k,
        LET(
            previous, TAKE(triangle, -1),
            left,     HSTACK(previous, 0),
            right,    HSTACK(0, previous),
            IFNA(VSTACK(triangle, left + right), "")
        )
    )
)

Resources