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## Array functions

Starting with gnuplot version 6, an array can be passed to a function or returned by a function. For example a simple dot-product function acting on two equal-sized numerical arrays could be defined:

         dot(A,B) = (|A| != |B|) ? NaN : sum [i=1:|A|] A[i] * B[i]

Built-in functions that return an array include the slice operation array[min:max] and the index retrieval function index(Array,value).

         T = split("A B C D E F")
         U = T[3:4]
         print T
            [ "A", "B", "C", "D", "E", "F" ]
         print U
            [ "C", "D" ]
         print index( T, "D" )
            4

Note that T and U in this example are now arrays, whether or not they had been previously declared.