# Operator::dB
Operator to support decibel (dB) arithmetic.
use Operator::dB;
put 100 + 3dB;
# 199.52623149688796
put 100 - 3dB;
# 50.11872336272723
put 10dB + 20dB;
# 20.413927dB
## Description
The interface tries to be intuitive while avoiding ambiguity. For example, the
following makes sense (adding 3dB is approximately equivalent to doubling).
10 + 3dB
# 19.952623149688794
But the following doesn't make sense. It could represent either `13dB` or
`10.8dB` (i.e. `3dB + 10dB`).
3dB + 10 # DOESN'T WORK!
All supported operations are discussed in the following subsections.
### Addition and subtraction on numbers
Adding or subtracting decibel values to and from numbers (of `Numeric` type)
scales the number by the corresponding decibel gain:
put 100 + 3dB;
# 199.52623149688796
put 100 - 3dB;
# 50.11872336272723
### Addition and subtraction on decibels
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 => 0.365...)
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)
## Caveats
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 AFAIK.
## See also
- [Operators in Raku](https://docs.raku.org/language/operators)
- [Creating operators in Raku](https://docs.raku.org/language/optut)