Dealing with accuracy problems in floating-point numbers
c++, floating-accuracy, floating-point
Solution
A very simple and effective way to round a floating point number to an integer:
int rounded = (int)(f + 0.5);
Note: this only works if `f` is always positive. (thanks j random hacker)
Problem
I was wondering if there is a way of overcoming an accuracy problem that seems to be the result of my machine's internal representation of floating-point numbers: For the sake of clarity the problem is summarized as: ``` // str is "4.600"; atof( str ) is 4.5999999999999996 double mw = atof( str ) // The variables used in the columns calculation below are: // // mw = 4.5999999999999996 // p = 0.2 // g = 0.2 // h = 1 (integer) int columns = (int) ( ( mw - ( h * 11 * p ) ) / ( ( h * 11 * p ) + g ) ) + 1; ``` Prior to casting to an integer type the result of the columns calculation is 1.9999999999999996; so near yet so far from the desired result of 2.0. Any suggestions most welcome.