# 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.