Apparatus and method for calculating an exponential calculating result of a floating-point number

An apparatus for calculating an exponential calculating result for a base 2 floating-point number wherein the floating-point number is represented in the format of (−1)Sx·2Ex·mx and the exponential calculating result Y is represented in the format of (−1)Sy·2Ey·my, where Sx is a sign of the floating-point number, Sy is a sign of the exponential calculating result, Ex is an exponent of the floating-point number, Ey is an exponent of the exponential calculating result, mx is a mantissa of the floating-point number, my is a mantissa of the exponential calculating result, 1≦mx<2 and 1≦my<2, the apparatus comprising:

• a transforming device for receiving the sign of a floating-point number, the exponent of the floating-point number and the mantissa of the floating-point number, transforming the floating-point number to an integer part and a fractional part, and outputting the integer part and the fractional part, wherein the fractional part is an N-bit number and divided into K parts which have N1, N2, . . . , NK bits respectively, wherein N=N1+N2+ . . . +NK;
• K exponential tables, each of the exponential tables for receiving one of the K parts divided from the fractional part and outputting a result;
• and
• a multiplier for receiving all results from the exponential tables and outputting the mantissa of the exponential calculating result;
• wherein the integer part outputted from the transforming device is the exponent of the exponential calculating result, the sign of the exponential calculating result is 0 and the N, K, N1, N2, . . . , NK are natural numbers.