Unformatted text preview: Zero • Recall first used as a medial placeholder (but not alone) by Babylonians in 300 BC. • Mayans also had it about 300 BC. • Ptolemy used a genuine zero in 130 AD in a hybrid Greek/Babylonian system. • Brahmagupta in 628 AD used first decimal zero, and this got transmitted to Arabian math ematicians and subsequently to the West. (Brahmagupta himself was influenced by the Babylonians’ medial zero and Ptolemy’s sexagesimal zero.) Negative Numbers • Hard for us to imagine doing without them, but there is a sense in which it is natural do so. We have been trained to see their usefulness. (Flatland?) • Needed for solving linear equations. • Useful in commerce and were thus used before completely accepted by mathematicians. • Used in first century BC by Chinese. (Before they had zero!) Red and black rods for positive and negative, respectively, (reverse of us) but a rod of length zero easily gets lost....
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 Fall '10
 wen
 Complex Numbers, Wallis, Complex number, ﬁrst century BC

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