C

n=sqrt(1+1.2542/(1-0.013862/pow(x,2)))

Python

n=(1+1.2542/(1-0.013862/x**2))**.5

Fortran

n=SQRT(1+1.2542/(1-0.013862/x**2))

MATLAB

n=sqrt(1+1.2542./(1-0.013862./x.^2))

LaTeX

n^2-1=\frac{1.2542λ^2}{λ^2-0.013862}