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47 lines
834 B
Plaintext
47 lines
834 B
Plaintext
NAME
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segment - segment from and to specified elements of a list
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SYNOPSIS
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segment(x, y, z)
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TYPES
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x list
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y, z int
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return list
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DESCRIPTION
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For 0 <= y < size(x) and 0 <= z < size(x), segment(x, y, z)
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returns a list for which the values of the elements are those
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of the segment of x from x[[y]] to x[[z]]. If y < z, the
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new list is in the same order as x; if y > z, the order is
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reversed.
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If y < z, x == join(head(x,y), segment(x,y,z), tail(x, size(x) - z - 1)).
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EXAMPLE
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> A = list(2, 3, 5, 7, 11)
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> segment(A, 1, 3)
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list (3 members, 3 nonzero):
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[[0]] = 3
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[[1]] = 5
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[[2]] = 7
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> segment(A, 3, 1)
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list (3 members, 3 nonzero):
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[[0]] = 7
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[[1]] = 5
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[[2]] = 3
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LIMITS
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0 <= y < size(x)
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0 <= z < size(x)
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LIBRARY
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none
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SEE ALSO
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head, tail
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