Reference Docs

This section contains detailed reference documentation on Quantity, QuantityPoint, units, dimensions, magnitudes, and other core library abstractions. The main folder is reserved for things that end users will routinely interact with. Implementation details will be documented in a detail sub-folder.

Here’s a guide to the main reference pages.

• Quantity. This is the main type you’ll use to replace raw numeric types. It acts like a numeric type, but it keeps track of its units.

  • QuantityPoint. Similar to Quantity, but for modeling affine space types. This means you can subtract two QuantityPoints, and you’ll get a Quantity (just like subtracting two points gives a displacement). Practically speaking, this is essential for dealing with temperatures, and useful for a couple other dimensions such as pressures and distances.

• Constant. A constant quantity which is known at compile time, and represented by a symbol. Supports exact symbolic arithmetic at compile time, and a perfect conversion policy to Quantity types.

• Unit. A type which represents a unit of measure.

• Magnitude. A special kind of compile-time number, which we use to represent ratios between pairs of units. Can handle many challenging use cases which std::ratio can’t, and which are necessary for units libraries — such as irrational numbers, or extremely large or small numbers.

• Prefix. A term that can be applied to the beginning of a unit, to make a new unit with a specified relative size. For example, centi is a prefix whose relative magnitude is $1/100$, and a centi(meter) is a new unit which is one one-hundredth of a meter.

• Math functions. We provide many common mathematical functions out of the box.

See the sidebar for the complete list of pages.