etl/docs/maths/Invert.md

title
Invert

{{< callout type="info">}} Header: invert.h
Since: 20.9.0
{{< /callout >}}

Invert an input range.

template <typename TInput>
class invert : public etl::unary_function<TInput, TInput>

``TInput``` The input data type.

invert() 

Description
offset = 0 minuend = etl::numeric_limits<TInput>::is_signed) ? TInput(0) : etl::numeric_limits<TInput>::max())

If the type is signed then the input values have their sign changed.
i.e. 10 => -10, -10 => 10.
If the type is unsigned then the input values are subtracted from the type's maximum value.

---

invert(TInput offset, TInput minuend)

Description
Sets the offset and minuend.

---

TInput operator()(TInput value) const

Description
Invert a value. Calculates minuend - (value - offset)

Example

std::array<int, 10> input = 
{ 
  10, 11, 12, 13, 14, 15, 16, 17, 18, 19
};

std::array<int, 10> output;

etl::invert<int> invert(10, 100); // offset = 10, minuend = 100

std::transform(input.begin(), input.end(), output.begin(), invert);

// output = 100.0, 99.0, 98.0, 97.0, 96.0, 95.0, 94.0, 93.0, 92.0, 91.0