# sim-lib-numbers-complex
In one line: It gives you complex numbers, the two-part numbers that engineering and physics rely on.
## What it gives you
Some problems, like waves, signals, and rotations, are far easier to describe with numbers that have both a real and an imaginary part. This gives you those complex numbers and the arithmetic that goes with them, so you can add, multiply, and combine them naturally. Just as importantly, ordinary whole numbers, decimals, and fractions can rise into complex form whenever a calculation needs it, so you can freely mix a plain value with a complex one and get a sensible answer. It is the meeting point where the everyday number kinds gain their extra dimension.
## Why you will be glad
- Wave, signal, and rotation problems become straightforward to express and compute.
- Plain numbers and complex ones combine smoothly, with no manual conversion.
- You have a complete two-part number kind ready whenever a problem demands it.
## Where it fits
This is the complex-number domain of the SIM number stack, and it sits at the top of the scalar ladder. Integers, decimals, and fractions all promote into it, so it acts as the destination where the simpler kinds come together when a calculation reaches for the complex plane.