VECTOR CALCULATION CIRCUIT CAPABLE OF RAPIDLY CARRYING OUT VECTOR CALCULATION OF THREE INPUT VECTORS

In a vector calculation circuit for use in a vector addition of first, second, and third vectors each of which is composed of an identical number to one another, a first adder circuit (26) comprises a carry save adder which carries out a carry save addition of a set of three components selected from the first through third vectors to produce a local sum and a carry collectively as a result of the carry save addition. The local sum and the carry is successively summed up by a second adder circuit (27) to produce a primary sum which forms an output vector. The primary sum may successively be sent back to the first adder circuit as the third vector. A selector circuit may be connected to the first adder circuit to select the first through third vectors and a fixed value of zero and to selectively add either two of the first through third vectors or three of them. Alternatively, a pair of selectors may be included to select either the first and the second vectors or the local sum and the carry.