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 # 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`.