Operator::dB is a Raku operator to support decibel (dB)
arithmetic.
$ zef install Operator::dB
$ raku -M Operator::dB
> 100 + 30dB
100000
> 100 - 30dB
0.1
> put 10dB + 20dB
20.413927dB
The interface tries to be intuitive while avoiding ambiguity. For example,
> 10 + 20dB
1000
makes sense because adding 20dB is multiplying by 10^2, but,
> 20dB + 10 # DOESN'T WORK!
doesn't, because it ambiguously represents both of the following:
30.0dBi.e.(20 + 10)dB20.4dBi.e.20dB + 10dB
All the examples in this README were obtained using the Raku REPL. Please note, to use the REPL with custom operators like this one, you'll need Raku 2025.03 or later because of this bug in prior versions.
To install the latest version, run:
$ zef install Operator::dB
Adding or subtracting decibel values to and from numbers (of Numeric type)
scales the number by the corresponding decibel gain:
> 1 + 40dB
10000
> 1 - 40dB
0.0001
Decibels can be added to, or subtracted from, each other.
This type of operation returns an Operator::dB::Decibel wrapper object:
> my $foo = 3dB + 2dB - 1dB
Operator::dB::Decibel.new(x => 10, y => 0.36571819272302736e0)
and you can get the decibel value itself with .dB:
> $foo.dB
3.6571819272302735
or by stringification:
> "The gain is: $foo"
The gain is 3.657182dB
or by defining your own format with .fmt:
> $foo.fmt("%.1f dB(A)")
3.7 dB(A)
This package exports overloads to built-in operators, which is potentially
reckless. But the operator signatures all contain at least one
Operator::dB::Decibel object -- which is not built-in -- so it should be
fine!
The Num method is not implemented on the wrapper class, so many built-in
numerical operations don't work, e.g. 1dB * 1. This is a necessary limitation
because decibel arithmetic is only semantically valid for addition and
subtraction as far as the author is aware.