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Hex Value $BB2C
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    • FR: Δliste(

    ΔList(

    Overview

    Returns a list containing the differences between consecutive elements in list.

    Availability: Token available everywhere.

    Syntax

    ΔList(list)

    Arguments

    NameTypeOptional
    Δ
    listlist

    Location

    2nd, list, OPS, 7:List(

    Description

    ΔList( calculates the differences between consecutive terms of a list, and returns them in a new list.

    ΔList({0,1,4,9,16,25,36})
    {1 3 5 7 9 11}

    Advanced Uses

    The ΔList( command is very nearly the inverse of the cumSum( command, which calculates the cumulative sums of a list. For any list, ΔList(cumSum(list)) will return the same list, but without its first element:

    ΔList(cumSum({1,2,3,4,5,6,7}))
    {2 3 4 5 6 7}

    Removing the first element would otherwise be a difficult procedure involving the seq( command, so this is a useful trick to know.

    If a list is sorted in ascending order, min(ΔList(list)) will return 0 (false) if there are repeating values in the list, and a value corresponding to true if they are all distinct. The number of repeating elements can be determined similarly via 1+sum(0≠ΔList(list)) (again, so long as the list is sorted).

    Error Conditions

    Source: parts of this page were written by the following TI|BD contributors: DarkerLine, GoVegan, kg583, Timothy Foster.

    History

    Calculator OS Version Description
    TI-83 0.01013 Added
    Last update: September 30, 2023 15:38:51
    Created: February 23, 2023 23:15:01
    Authors: Adrien Bertrand