FOR Indexed

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FOR Indexed

            [SIC\]FOR Loop_Variable n1 n2 n3 TO n4 BY n5 n6 TO n7

            The loop specified in this example will execute  for  the  following
            values of the index :
                    n1
                    n2
                    n3, n3 + n5, n3 + 2 n5, n3 + 3 n5, ... , n4
                    n6, n6 + 1, n6 + 2, ... , n7
            (assuming that n4-n3 is a multiple of n5, n7-n6 an integer).

        Loop variables are undefined outside the loop, and must not be previous-
        ly defined. Here, the loop variables are Double Precision  numbers,  and
        non-integer start, end, and step can be used. Invalid ranges are ignored
        at execution time: e.g. in the previous example, the loop would  not  be
        executed for n3 TO n4 BY n5 if n5*(n4-n3) < 0, but no error is signaled.
        Increments of 0 produce an error. The index of the loop will be  substi-
        tuted to the loop variable Loop_Variable during loop execution.