ClaireGuerin / rand-round

Random rounding of numbers with probability of ceiling vs flooring proportional to decimal

Random rounding

Random rounding of floating-point numbers with probability of ceiling vs flooring proportional to decimal. For Xiaoyan's code.

Examples

• 7.5 becomes 7 (floored) with 50% chance, and becomes 8 (ceiled) with 50% chance.
• 6.6 becomes 6 (floored) with 40% chance, and becomes 7 (ceiled) with 60% chance.
• -2.3 becomes -2 (floored) with 30% chance, and becomes -3 (ceiled) with 70% chance.

How to use

src/Round.hpp contains the function randround::round, which takes as arguments the value to be rounded stochastically, and the random number generator.

main.cpp is an example use of that function. It feeds it the std::default_random_engine and calls it multiple times (10'000) on different values (7.5, 6.6, -2.3). It then prints the percentage of flooring versus ceiling in each case.

Result

Random rounding of 7.5:  
 7 ************ 50.06%  
 8 ************ 49.94%  
Random rounding of 6.6:  
 6 ********* 39.46%  
 7 *************** 60.54%  
Random rounding of -2.3:  
-3 ******* 30.17%  
-2 ***************** 69.83%