rain.math.float

Decimal floating point math implemented in Solidity/Yul.

Context

IEEE 754 Floating point math such as is used by JavaScript is usually bad in finance for a few reasons.

• The decimal representations of amounts and prices of things don't have exact representations in the underlying binary
• Mathematical nonsense like dividing by 0 gives "special" values like Infinity and NaN which then propagate throughout business logic rather than erroring

This lib provides decimal floats that do error upon nonsense.

Everything you can type into a webform, or Rainlang, etc. that fits into 224 bit coefficient with 32 bit exponent (huge values for both) will be exactly represented.

This doesn't mean the floating point math is perfect, for example 1/3 will still be some imprecise rounded 0.3333... value as we don't have infinite precision.

It does mean that 0.2+0.7 is 0.9 rather than 0.8999999999999999 because the fractional values use decimal exponents rather than binary exponents.

e.g. 0.2 internally is something like 2e-1 and 0.7 is 7e-1 so internally the result is 2+7 which is 9 with an exponent of -1.