I don’t have a rounding function in my programming language. I want to take the result of a floating point operation, find the least significant digit and round up based on that. What I’ve found so far on the Internet are functions that just add .5, which seems pretty inaccurate.
- How do I find the least significant digit?
- Once I have that digit, I need to determine if it is > 5 or less than 5.
- If it is greater than or equal to 5, then I need to check the next digit and increment it if it is greater than 5, till I get to the decimal point and use the same determination on the number (but as a whole number, so if it is 65.444445 then it should be 66 I think) to the right of the decimal place. At least this is what seems to make sense, but maybe I’m overcomplicating this?
First: You and the problem at hand decide how many significant digits there are. The least significant digit is simply the last digit that’s a significant digit.
Second: Since you know how to round to the nearest integer, then you can round to any significant digit by multiplying the number by a power of 10 before, and multiplying by the inverse power of 10 after.
If, for example, you have decided that there should be 4 significant digits, then the least significant digit is the fourth digit.
The number 1234567890 (10 digits) may be rounded to that digit by:
Third: You’re overcomplicating this. 65.444445 is closer to 65 than it is to 66. It’s less than 65.5, which is the midpoint between 65 and 66.