# Command: Part

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Name:

    Part - returns a sub-array of an array

Synopsis:

    array1 array2 Part -> array3

Examples:

      [ [3 5 6 9] [11 4 7 2] [-9 1 8 10] ]  [ [1 3] [2 3] ] Part  --> [[5 6] [1 8]]
      [ [3 [-12 -19] 6 9] [11 4 7 2] [-9 1 8 10] ]  [ 1 2 2] Part --> -19
      [3 4 5 6 7] [-2] Part	 --> 6
      [3 [-9 -12] 5 6 7] [2] Part	 --> [-9 -12]
      [3 [-9 -12] 5 6 7] [2 2] Part	 --> -12
      [3 [-9 -12] 5 6 7] [[2 3]] Part	 --> [[-9 -12] 5]
      [3 [-9 -12] 5 6 7] [[2 3 2]] Part	 --> [[-9 -12] 5 [-9 -12]]
      [ [3 5 6 9] [11 4 7 2] [-9 1 8 10] ]  [ 1 []  ] Part   --> []
      [ [3 5 6 9] [11 4 7 2] [-9 1 8 10] ]  [ [] 1 ] Part	 --> []
      [3 [5 -12] 6 9]  [ [ 2 ] ] Part	 --> [[5 -12]]
      [3 [5 -12] 6 9]  [ [ 2 ] 2] Part	 --> [-12]
      [ [3 5 6 9] [11 4 7 2] [-9 1 8 10] ]  [ /All [3 2]  ] Part --> [[6 5] [7 4] [8 1]]

Description:

      Part returns a sub-array of array1 specified by
      array2. This function is an implementation of
      Mathematica's Part function. It can also be used
      to rearrange or copy parts of array1. Note,
      Mathematica-style functions in SLI use Mathematica
      index notation.

Parameters:

      array1 is an arbitrarily shaped array. In particular
      it does not need to be rectangular.

      array2 is an array [i,j, ...] where the i,j specify the
      selected elements on each level. Any i,j can itself be
      an array [i1,i2,....] specifying a list of elements on
      that level. When i is the literal /All, all elements on
      the corresponding level are returned. The first element
      on each level has index 1. Indices can also be specified
      counting from the end of the array, in this case the last
      element has index -1. Positive and neative indices can
      arbitrarily be intermixed.

      Alternatives: Function Part_a (undocumented) -> behaviour and
      synopsis are the same.

Bugs:

Remarks:

      Literal /All plays the role of the index specifier ':'
      in Matlab when used without arguments. Note, that
      Matlab in addition provides specifier 'end'.
      This is not necessary in the formalism of Mathematica
      because indices counting from the end of the array can be
      expressed by negative values.

References:

      [1] The Mathematica Book V4.0 "Part"

Author:

    Diesmann

FirstVersion:

    29.9.1999

SeeAlso:

- MathematicaToSliIndex

Source:

    /opt/conda/conda-bld/nest_1512418773968/work/nest-2.14.0/lib/sli/mathematica.sli

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