The normwise structured backward error of an approximate eigen-pair is defined and its explicit formula is given.
When a inverse function of monotone function can not show the explicit formula, the distribution density curve of continuous randon variable can be gained with a parametric equation.
The parameters of canonical polynomials can be obtained by using explicit formulae.
For the first time, the inversion-free explicit formulae are derived for genus 3 HECC in projective coordinate system.
