# arraylib::IndexWrap

Name:
`arraylib::IndexWrap - project a cyclic index value onto interval [0,N).       Synopsis:  index N CyclicValue -> normindex`
Examples:
```   -6 3 IndexWrap   -> 0    -5 3 IndexWrap   -> 1    -4 3 IndexWrap   -> 2    -3 3 IndexWrap   -> 0    -2 3 IndexWrap   -> 1    -1 3 IndexWrap   -> 2    0 3 IndexWrap   -> 0    1 3 IndexWrap   -> 1    2 3 IndexWrap   -> 2    3 3 IndexWrap   -> 0    4 3 IndexWrap   -> 1    5 3 IndexWrap   -> 2    6 3 IndexWrap   -> 0
```
Description:
```   "IndexWrap" projects a cyclic integer index in the range (-oo,oo),    of periodicy N, onto its norm interval [0,N).       This function can be used to "wrap around" array indices in order to    index an array       Alternatives: Function IndexWrap_i_i (undocumented) -> behaviour and    synopsis are the same, except that no warnings or error messages are    thrown.
```
Parameters:
```   In : index: integer value in (-oo,oo).       N: Peroidicity of the cyclic index.    "index" is projected on the half-open interval [0,N).    N must be positive (and different from 0).       Out: The cyclic equivalent of the given index, regarding period N.
```
Diagnostics:
```   N must be positive (and different from 0). If N <= 0, /RangeCheck is raised.    Note that the variant IndexWrap_i_i does not do this check for    efficiency, and will break or yield invalid results in this case.
```
Remarks:
```   This function behaves like Mathematica's Mod function (which is    different from the mathematical definition of MOD).
```
Availability:
```   "Namespace"-dictionary "arraylib".
```
Author:
```Ruediger Kupper
```
FirstVersion:
```14.2.2003 (Einstein's birthday)
```
SeeAlso: Source:
`/home/graber/work-nest/nest-git/nest-simulator/lib/sli/arraylib.sli`