Rafael Bombelli

Rafael Bombelli (baptised in 1526, died in 1572) was an Italian mathematician born in Bologna, the author of a treatise on algebra and a central figure in the understanding of imaginary numbers. He was the oldest of six children of a wool merchant and received no college education, being taught instead by an engineer and architect, Pier Francesco Clementi. Finding that the leading algebra works of his day were not carefully and thoroughly set out, he wrote his book Algebra, published in 1572, so that anyone could follow it. In it he solved equations by the method of del Ferro and Tartaglia, introduced wording that preceded the symbols for the square roots of plus and minus one, and was the first European to write down the rules for computing with negative numbers. He also used a form of index notation in print for the first time. He died in Rome.