He introduced Arabic numerals to the West.
This man's namesake identity is that the product of two sums of squares is itself a sum of squares. Dijkstra's [DIKE-straw's] algorithm is often implemented using a heap named for this man. He introduced Arabic numerals to the West. The matrix 1, 1, 1, 0, gives this man's numbers when exponentiated, and has the golden ratio as an eigenvalue. This man's (*) numbers are formed by the shallow diagonals on Pascal's triangle. A classic example of recursion is his relation that a-sub-n plus-one equals a-sub-n plus a-sub-n-minus-one. That pattern models the growth rate of rabbits and starts 1, 1, 2, 3, 5, 8. For 10 points, name this Italian namesake of a sequence.
This man's namesake identity is that the product of two sums of squares is itself a sum of squares.
Fibonacci [or Leonardo da Pisa; prompt on Brahmagupta until “heap” is read]