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.\" ========================================================================
.\"
.IX Title "Math::PlanePath::Base::Digits 3pm"
.TH Math::PlanePath::Base::Digits 3pm "2021-01-23" "perl v5.32.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Math::PlanePath::Base::Digits \-\- helpers for digit based paths
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 3
\& use Math::PlanePath::Base::Digits \*(Aqdigit_split_lowtohigh\*(Aq;
\& foreach my $digit (digit_split_lowtohigh ($n, 16)) {
\& }
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This is a few generic helper functions for paths based on digits or
powering.
.PP
They're designed to work on plain Perl integers and floats and there's some
special case support for \f(CW\*(C`Math::BigInt\*(C'\fR.
.SH "EXPORTS"
.IX Header "EXPORTS"
Nothing is exported by default but each function below can be as in the
usual Exporter style,
.PP
.Vb 1
\&    use Math::PlanePath::Base::Digits \*(Aqround_down_pow\*(Aq;
.Ve
.PP
(But not \f(CW\*(C`parameter_info_radix2()\*(C'\fR, for the reason described below.)
.SH "FUNCTIONS"
.IX Header "FUNCTIONS"
.SS "Generic"
.IX Subsection "Generic"
.ie n .IP """($power, $exponent) = round_up_pow ($n, $radix)""" 4
.el .IP "\f(CW($power, $exponent) = round_up_pow ($n, $radix)\fR" 4
.IX Item "($power, $exponent) = round_up_pow ($n, $radix)"
.PD 0
.ie n .IP """($power, $exponent) = round_down_pow ($n, $radix)""" 4
.el .IP "\f(CW($power, $exponent) = round_down_pow ($n, $radix)\fR" 4
.IX Item "($power, $exponent) = round_down_pow ($n, $radix)"
.PD
Return the power of \f(CW$radix\fR equal to or either higher or lower than \f(CW$n\fR.
For example
.Sp
.Vb 4
\&   ($pow, $exp) = round_down_pow (260, 2);
\&   # $pow==512  # the next higher power
\&   # $exp==9    # the exponent in that power
\&   # 2**9=512 is next above 260
\&
\&   ($pow, $exp) = round_down_pow (260, 2);
\&   # $pow==256  # the next lower power
\&   # $exp==8    # the exponent in that power
\&   # 2**8=256 is next below 260
.Ve
.ie n .IP """@digits = digit_split_lowtohigh ($n, $radix)""" 4
.el .IP "\f(CW@digits = digit_split_lowtohigh ($n, $radix)\fR" 4
.IX Item "@digits = digit_split_lowtohigh ($n, $radix)"
.PD 0
.ie n .IP """@bits = bit_split_lowtohigh ($n)""" 4
.el .IP "\f(CW@bits = bit_split_lowtohigh ($n)\fR" 4
.IX Item "@bits = bit_split_lowtohigh ($n)"
.PD
Return a list of digits from \f(CW$n\fR in base \f(CW$radix\fR, or in binary.  For
example,
.Sp
.Vb 2
\&   @digits = digit_split_lowtohigh (12345, 10);
\&   # @digits = (5,4,3,2,1)   # decimal digits low to high
.Ve
.Sp
If \f(CW\*(C`$n==0\*(C'\fR then the return is an empty list.  The current code expects \f(CW\*(C`$n
>= 0\*(C'\fR.
.Sp
\&\*(L"lowtohigh\*(R" in the name tries to make it clear which way the digits are
returned.  \f(CW\*(C`reverse()\*(C'\fR can be used to get high to low instead (see
\&\*(L"reverse\*(R" in perlfunc).
.Sp
\&\f(CW\*(C`bit_split_lowtohigh()\*(C'\fR is the same as \f(CW\*(C`digit_split_lowtohigh()\*(C'\fR called
with radix=2.
.ie n .IP """$n = digit_join_lowtohigh ($arrayref, $radix)""" 4
.el .IP "\f(CW$n = digit_join_lowtohigh ($arrayref, $radix)\fR" 4
.IX Item "$n = digit_join_lowtohigh ($arrayref, $radix)"
.PD 0
.ie n .IP """$n = digit_join_lowtohigh ($arrayref, $radix, $zero)""" 4
.el .IP "\f(CW$n = digit_join_lowtohigh ($arrayref, $radix, $zero)\fR" 4
.IX Item "$n = digit_join_lowtohigh ($arrayref, $radix, $zero)"
.PD
Return a value made by joining digits from \f(CW$arrayref\fR in base \f(CW$radix\fR.
For example,
.Sp
.Vb 3
\&   @digits = (5,4,3,2,1)   # decimal digits low to high
\&   $n = digit_split_lowtohigh (\e@digits, 10);
\&   # $n == 12345
.Ve
.Sp
Optional \f(CW$zero\fR can be a 0 of an overloaded number type such as
\&\f(CW\*(C`Math::BigInt\*(C'\fR to give a returned \f(CW$n\fR of that type.
.SS "Subclassing"
.IX Subsection "Subclassing"
.ie n .IP """$aref = parameter_info_array()""" 4
.el .IP "\f(CW$aref = parameter_info_array()\fR" 4
.IX Item "$aref = parameter_info_array()"
Return an arrayref of a \f(CW\*(C`radix\*(C'\fR parameter, default 2.  This is designed to
be imported into a PlanePath subclass as its \f(CW\*(C`parameter_info_array()\*(C'\fR
method.
.Sp
.Vb 2
\&    package Math::PlanePath::MySubclass;
\&    use Math::PlanePath::Base::Digits \*(Aqparameter_info_array\*(Aq;
.Ve
.Sp
The arrayref is
.Sp
.Vb 10
\&    [ { name      => \*(Aqradix\*(Aq,
\&        share_key => \*(Aqradix_2\*(Aq,
\&        display   => \*(AqRadix\*(Aq,
\&        type      => \*(Aqinteger\*(Aq,
\&        minimum   => 2,
\&        default   => 2,
\&        width     => 3,
\&        description => \*(AqRadix (number base).\*(Aq,
\&      }
\&    ]
.Ve
.ie n .IP """$href = Math::PlanePath::Base::Digits::parameter_info_radix2()""" 4
.el .IP "\f(CW$href = Math::PlanePath::Base::Digits::parameter_info_radix2()\fR" 4
.IX Item "$href = Math::PlanePath::Base::Digits::parameter_info_radix2()"
Return the single \f(CW\*(C`radix\*(C'\fR parameter hashref from the info above.  This can
be used when a subclass wants the radix parameter and other parameters too,
.Sp
.Vb 9
\&    package Math::PlanePath::MySubclass;
\&    use constant parameter_info_array =>
\&      [
\&       { name            => \*(Aqsomething_else\*(Aq,
\&         type            => \*(Aqinteger\*(Aq,
\&         default         => \*(Aq123\*(Aq,
\&       },
\&       Math::PlanePath::Base::Digits::parameter_info_radix2(),
\&      ];
.Ve
.Sp
If the \*(L"description\*(R" part should be more specific or more detailed then it
could be overridden with for example
.Sp
.Vb 3
\&   { %{Math::PlanePath::Base::Digits::parameter_info_radix2()},
\&     description => \*(AqRadix, for both something and something.\*(Aq,
\&   },
.Ve
.Sp
This function is not exportable since it's meant for a one-off call in an
initializer and so no need to import it for repeated use.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Math::PlanePath,
Math::PlanePath::Base::Generic
.PP
Math::BigInt
.SH "HOME PAGE"
.IX Header "HOME PAGE"
<http://user42.tuxfamily.org/math\-planepath/index.html>
.SH "LICENSE"
.IX Header "LICENSE"
Copyright 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Kevin Ryde
.PP
This file is part of Math-PlanePath.
.PP
Math-PlanePath is free software; you can redistribute it and/or modify it
under the terms of the \s-1GNU\s0 General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
.PP
Math-PlanePath is distributed in the hope that it will be useful, but
\&\s-1WITHOUT ANY WARRANTY\s0; without even the implied warranty of \s-1MERCHANTABILITY\s0
or \s-1FITNESS FOR A PARTICULAR PURPOSE.\s0  See the \s-1GNU\s0 General Public License for
more details.
.PP
You should have received a copy of the \s-1GNU\s0 General Public License along with
Math-PlanePath.  If not, see <http://www.gnu.org/licenses/>.