Kevin Ryde > Math-NumSeq > Math::NumSeq::MephistoWaltz

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NAME ^

Math::NumSeq::MephistoWaltz -- Mephisto waltz sequence

SYNOPSIS ^

 use Math::NumSeq::MephistoWaltz;
 my $seq = Math::NumSeq::MephistoWaltz->new;
 my ($i, $value) = $seq->next;

DESCRIPTION ^

The Mephisto waltz sequence, being the mod 2 count of ternary digit 2s in i.

    0,0,1, 0,0,1, 1,1,0, ...
    starting i=0

i=0 has no 2s so value=0, and likewise i=1 value=0. Then i=2 has one 2 so value=1.

The sequence can also be expressed as starting with 0 and repeatedly expanding

    0 -> 0,0,1
    1 -> 1,1,0

So

    0
    0,0,1
    0,0,1, 0,0,1, 1,1,0,
    0,0,1, 0,0,1, 1,1,0, 0,0,1, 0,0,1, 1,1,0, 1,1,0, 1,1,0, 0,0,1

    |   original      |  |     copy        |  |     inverse     |
    +-----------------+  +-----------------+  +-----------------+

The effect of the expansion is keep the first third the same, append a copy of it, and append an inverse of it 0<->1.

FUNCTIONS ^

See "FUNCTIONS" in Math::NumSeq for behaviour common to all sequence classes.

$seq = Math::NumSeq::MephistoWaltz->new ()

Create and return a new sequence object.

Random Access

$value = $seq->ith($i)

Return the $i'th MephistoWaltz value, being the count mod 2 of the ternary digit 2s in $i.

$bool = $seq->pred($value)

Return true if $value occurs in the sequence, which simply means 0 or 1.

FORMULAS ^

The calculation can be made in a power-of-3 base like 9, 27, 81, etc instead of just 3. For example in base 9 digits 2, 5, 6, 7 have a one (mod 2) ternary 2. These base 9 digits correspond to the 1s in the initial sequence 0,0,1, 0,0,1, 1,1,0 shown above.

SEE ALSO ^

Math::NumSeq, Math::NumSeq::DigitSumModulo

HOME PAGE ^

http://user42.tuxfamily.org/math-numseq/index.html

LICENSE ^

Copyright 2011, 2012, 2013, 2014 Kevin Ryde

Math-NumSeq is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.

Math-NumSeq is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with Math-NumSeq. If not, see <http://www.gnu.org/licenses/>.

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