What does the C++ map() function do

Question

I am currently looking at the following code (which can be found here)

void MPU6050::CalibrateAccel(uint8_t Loops,uint8_t OffsetSaveAddress) {
  double kP = 0.15;
  double kI = 8;
  float x;
  x = (100 - map(Loops, 1, 5, 20, 0)) * .01;
  kP *= x;
  kI *= x;
  PID( 0x3B,  OffsetSaveAddress,  kP, kI,  Loops);
}

Specifically I am struggling to understand what the line:

x = (100 - map(Loops, 1, 5, 20, 0)) * .01;

is doing?

The best matching function I can find for map() is here but it doesn't appear to match the integer parameters that are being passed into the function.

Obviously ideally I would run this code but unfortunately I am yet unable to get this to compile.

Have I correctly found the function being invoked and what is the behaviour of this function with the given parameters? I assume this is a map() function similar to any other typical map function in other languages/frameworks such as python, jquery etc.

Could anyone guide me in the right direction?

Answer 1

map defined in math, re-maps a number from one range to another. Syntax is map(value, fromLow, fromHigh, toLow, toHigh)

So, map(Loops, 1, 5, 20, 0)) means the value of variable Loops will be initially searched between (1,5) but result will be between 20 to 0 since it is remapped.