Double kind coefficients as double kind rationals

[alozada]

@dsejas

I am wondering if there is a “best-practice” way to do this, specially from the numerical point of view. If there is any other advice you could give me on this type of code, it is much appreciated.

Maybe,
for coefficients (fixed), you could use an array with the attribute parameter
example:
real(dk), parameter :: coeff(*) = [0.1_dk, 0.2_dk, 0.3_dk]
or
real(dk), parameter :: coeff(3) = (/0.1_dk, 0.2_dk, 0.3_dk/)

a(1) = coeff(1) + coeff(2) * x + coeff(3) * x**2

you can also consult the post: Fortran Best Practice Minibook - #2 by Beliavsky