5G functions for Excel: Miscellaneous Math

BXL Excel LAMBDA Math

/*  Function        Description
    Aboutλ          About this module and links to online resources
    Fibonacciλ      Determine the nth number in a Fibonacci sequence 
*/




/*  FUNCTION NAME:  Aboutλ
    DESCRIPTION:*/  /**Displays the URL to this module's Gist which includes documentation*/
/*  ARGS:           *None
    EXAMPLE:        =About()
    ERRORS:         *None
    REVISIONS:      Date            Developer       Description  
                    Mar 03 2023     Craig Hatmaker  Original Development
*/
Aboutλ =TEXTSPLIT(
    "About:,BXL's math module. Suggested module name: BRM;" &
    "Version:,Mar 03 2023;" &
    "Gist URL:,https://gist.github.com/CHatmaker/https://gist.github.com/CHatmaker/e463f2edd734e40f78c39295e1ff8f7e;" &
    "Website:,https://sites.google.com/site/beyondexcel/home/excel-library/;" &
    ",;" &
    "Function,Description;" &
    "Aboutλ,Produces this table;" &
    "Fibonacciλ,Determine the nth number in a Fibonacci sequence" , 
    ",",
    ";"
    );
  
  
  

/*  FUNCTION NAME:  Fibonacciλ
    DESCRIPTION:*/  /**Determine nth number in Fibonacci sequence*/
/*  ARGS:           n               The position of the number to return within the Fibonacci sequence
    EXAMPLE         =Fibonacciλ(1)  Returns 0
                    =Fibonacciλ(2)  Returns 1
                    =Fibonacciλ(3)  Returns 1
                    =Fibonacciλ(4)  Returns 2
                    =Fibonacciλ(5)  Returns 3
                    =Fibonacciλ(6)  Returns 5
*/
Fibonacciλ = LAMBDA(
//  Parameter Declarations
    n,
//  LAMBDA's fromula
    LET(
    //  Validate Parameters
        ErrMsg,    "n must be a whole number greater than 0", 
        ErrTst,     If( Not(ISNUmber(n)), 
                        ErrMsg, 
                        If( n < 1 , ErrMsg, "")),
    //  Procedure
        Result,     If( ErrTst <> "", 
                        ErrMsg, 
                        IF(n <= 2, n - 1, Fibonacciλ(n - 1) + Fibonacciλ(n - 2))),
    //  Return Result
        Result
    )
 )