query: Who introduced the concept of complex numbers?
passage: Complex number
The solution in radicals (without trigonometric functions) of a general cubic equation contains the square roots of negative numbers when all three roots are real numbers, a situation that cannot be rectified by factoring aided by the rational root test if the cubic is irreducible (the so-called casus irreducibilis). This conundrum led Italian mathematician Gerolamo Cardano to conceive of complex numbers in around 1545,[16] though his understanding was rudimentary.
passage: Complex polytope
The regular complex polytopes were discovered by Shephard (1952), and the theory was further developed by Coxeter (1974).