The Arduino Language - Arduino Sketches: Tools and Techniques for Programming Wizardry - page 74

This function takes a value called value in a range between fromLow and
fromHigh , and remaps that value to a new range set by toLow and toHigh .
The clearest way to explain map() is with an example. Imagine a sensor, con-
nected to an analog pin. It outputs numbers from 0 to 1,023. How would you
convert this to a percentage? The map() function could do this in a single line.
result = map(sensorData, 0, 1023, 0, 100);
Mapping can also be used to invert value ranges:
result = map(sensorData, 1, 50, 50, 1);
pow()
pow() raises a number to the power of x .
double result = pow(float base, float exponent);
The base number and exponent are calculated as float , allowing for fractional
exponents. The result of this calculation is returned as a double .
sqrt()
sqrt() calculates the square root of a number.
double result = sqrt(x);
The number x can be of any numerical data type, and the result is expressed
as a double.
random()
Arduinos are capable of generating pseudo-random numbers using the ran-
dom() function:
result = random(max);
result = random(min, max);
This function takes one or two parameters specifying the range for the ran-
dom number to be chosen. If the min parameter is omitted, the result will be a
number between zero and max , otherwise the number will be between min and
max . The result is returned as a long .
Computers cannot generate purely random numbers, and instead use com-
plex algorithms. While the output may indeed seem random, it is actually a
sequence that is extremely long but always the same. To prevent your Arduino