In MATLAB, round, fix, floor, and ceil are all functions used for rounding numbers, but they differ in their behavior: round: rounds to the nearest integer. If the fractional part is exactly 0.5, it rounds to the nearest even integer. For example: round(3.5) % Output: 4 round(2.3) % Output: 2 fix: simply truncates the decimal part of the number, essentially removing it and keeping only the integer part. For example: fix(3.5) % Output: 3 fix(-3.5) % Output: -3 floor: always rounds down towards the nearest integer. For example: floor(3.5) % Output: 3 floor(2.1) % Output: 2 floor(-2.1) % Output: -3 ceil: always rounds up towards the nearest integer. For example: ceil(3.5) % Output: 4 ceil(2.1) % Output: 3 ceil(-2.1) % Output: -2 for negative values, the results appear a bit different for floor and ceil as floor (-2.1) will result in -3 instead of -2 (because -3 is smaller than -2), and ceil(-2.1) will result in -2 instead of -3 (because -2 is greater than -3). In simple words, one gives you the upper conversion of the number, and the other gives you the lower conversion of the number. Hopefully that will clear your confusion... Answer from Sibghat on mathworks.com