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## Operator::dB cpan:ALLSOPP last updated on 2019-09-15

Operator-dB-0.0.94/

# NAME

Operator::dB - Operator to support decibel (dB) arithmetic.

# SYNOPSIS

``````    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.