From India
Brahmagupta
His Brahmasphutasiddhanta (628 CE) sets out rules for calculating with zero and negative numbers.
His identity shows that multiplying two sums of two squares gives another sum of two squares, which is useful for this month’s research question.
Brahmagupta’s identity, 628 CE
No portrait of Brahmagupta survives, so we show the mathematics instead.
Where you’ll meet Brahmagupta here
They turn up beside problems and lessons on these topics.
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Pingala
His Chandahshastra counts the rhythms of Sanskrit verse as patterns of short and long syllables, an early cousin of binary numbers.
Later commentators such as Virahanka, Hemachandra and Halayudha drew from it what we call Fibonacci numbers and Pascal’s triangle.
Rhythms of 1, 2, 3, … beats
No portrait of Pingala survives, so we show the mathematics instead.