Adding apparatus having a high accuracy.

摘要

An apparatus (110) for adding a second input value (2) and a first input value (1) smaller than the second input value (2) comprises a memory device (107) for memorizing an under flow component; a first adder (103) for adding an output value from the memory device (107) and the first input value (1); a second adder (106) for adding an output value of the first adder (103) and the second input value (2); a first subtracter (105) for subtracting the second input value from an output value of the second adder (106); and a comparator (104) for comparing the output value of the first adder (103) and an output value of the first subtractor (105). It is judged by an output value of the comparator (104) whether or not the output value of the first adder (103) is memorized in the memory device (107).