[![Arduino CI](https://github.com/RobTillaart/MultiMap/workflows/Arduino%20CI/badge.svg)](https://github.com/marketplace/actions/arduino_ci) [![License: MIT](https://img.shields.io/badge/license-MIT-green.svg)](https://github.com/RobTillaart/MultiMap/blob/master/LICENSE) [![GitHub release](https://img.shields.io/github/release/RobTillaart/MultiMap.svg?maxAge=3600)](https://github.com/RobTillaart/MultiMap/releases) # MultiMap Arduino library for fast non-linear mapping or interpolation of values ## Description In Arduino applications often the value of a sensor is mapped upon a more usable value. E.g. the value of analogRead() is mapped onto 0 .. 5.0 Volt. This is done by the map function which does a linear interpolation. This means ```cpp output = C1 + input * C2 ``` As C1 and C2 are to be calculated Arduino has the **map()** that calculates the two variables runtime from two given mappings. ```cpp output = map(input, I1, I2, O1, O2): ``` In many cases when there is no linear mapping possible, as the 'points' are not on a single line. One needs non-linear math to calculate the output, **Multimap()** just does that. **out = Multimap(value, input, output, size)** needs two equal sized arrays of reference 'points', **input\[\]** and **output\[\]**, it looks up the input value in the input\[\] array and if needed it linear interpolates between two points of the output\[\] array. - The **input\[\]** array must have increasing values, there is no such restriction for the **output\[\]** array. - **Multimap()** automatically constrains the output to the first and last value in the **output\[\]** array. ## Operation See examples Please note the fail example as this shows that in the intern math overflow can happen. ## TODO Investigate class implementation for performance.