C

n=sqrt(1+3.1218393/(1-pow(0.1807/x,2)))

Python

n=(1+3.1218393/(1-(0.1807/x)**2))**.5

Fortran

n=SQRT(1+3.1218393/(1-(0.1807/x)**2))

MATLAB

n=sqrt(1+3.1218393./(1-(0.1807./x).^2))

LaTeX

n^2-1=\frac{3.1218393λ^2}{λ^2-0.1807^2}