...one of the most highly
regarded and expertly designed C++ library projects in the
world.

— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards

The Sinus Cardinal
family of functions (indexed by the family of indices ```
a
> 0
```

) is defined by

it sees heavy use in signal processing tasks.

By analogy, the Hyperbolic
Sinus Cardinal family of functions (also indexed by the family
of indices `a > 0`

) is defined by

These two families of functions are composed of entire functions.

These functions (sinc_pi and sinhc_pi) are needed by our implementation of quaternions and octonions.

Sinus Cardinal of index pi (purple) and Hyperbolic Sinus Cardinal of index pi (red) on R