Supergolden ratio

The Supergolden ratio, often denoted by the symbol \( \xi \) or \( \Phi_s \), is a mathematical concept that generalizes the golden ratio. It is defined as the positive root of the polynomial equation \( x^3 - x - 1 = 0 \). The value of the Supergolden ratio is approximately \( 1.8392867552 \).