Vectors, Matrices, and Tables > Working With Arrays > About Working With Arrays
  
About Working With Arrays
When you evaluate a large array, only the first 12 rows and columns are initially displayed. The presence of additional elements in the array is indicated by three dots that appear on the top-left corner or the bottom-right corner of the array. You can resize the array to view hidden elements and you can view the row and column indices. Arrays begin with index 0 by default. You can change the index by adjusting the built-in ORIGIN variable.
For ORIGIN=0, the last index of a vector is length(v) -1.
A range variable that starts with a value greater than ORIGIN, or ends with a value less than the length of the array, does not cover every element of the array.
The value of ORIGIN dictates which array elements can exist. For example, using the default settings, there cannot be an array element –1. If you evaluate the expression M-1, an error message appears.
Additional Information
You can think of the ORIGIN system variable as a hidden argument to some functions and operators. The value of ORIGIN causes such functions and operators to return different results.
The following functions explicitly require the specification of a row or column index:
Lookup functions—hlookup and vlookup.
Sort functions—csort and rsort.
Image processing functions—subcolor, dilate, gray_dilate, erode, and gray_erode.
The following functions do not require the specification of a row or column index, but are nonetheless affected by the value of ORIGIN:
The antisymmetric tensor function e.
The following operators require the specification of a row or column index, and their result is affected by the value of ORIGIN:
Vector and matrix operators—The column, row, and index operators: