| Property | Value |
|---|---|
| Hex Value | $BB2C |
| Categories | |
| Localizations |
|
ΔList(
Overview
Returns a list containing the differences between consecutive elements in list.
Availability: Token available everywhere.
Syntax
ΔList(list)
Arguments
| Name | Type | Optional |
|---|---|---|
| Δ | ||
| list | list |
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
- ERR:INVALID DIM is thrown if ΔList( is run on a single element list.
Related Commands
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 |