The proposed 2 deg cone fundamentals are based on the Stiles & Burch (1955) 2 deg color matching functions.
From Table A of Stockman, MacLeod and Johnson (1993) Journal of the Optical Society of America A, 10, 2491-2521
Columns 2, 3 and 4: logarithms of proposed S-cone (S), M-cone (M) and L-cone (L) fundamentals based on the Stiles-Burch (1955) , and 2-deg CMFs according to the following equations:
The S-cone sensitivities have been extended at λ>525 nm by using the following function:
(where λ is the wavelength in nm).
By adding columns 2 and 3 with weights equal to 0.68273 for L and 0.35235 for M a reasonable approximation to the shape of the CIE modified VM(l) can be obtained.
All coefficients given above have been scaled so that in energy units the interpolated peak cone sensitivities are equal to 1.
Stiles, W. S. & Burch, J. M. (1955). Interim report to the Commission Internationale de l'Eclairage Zurich, 1955, on the National Physical Laboratory's investigation of colour-matching. Optica Acta, 2, 168-181.
Stiles, W. S. & Burch, J. M. (1959). NPL colour-matching investigation: Final report. Optica Acta, 6, 1-26.
Stockman, MacLeod & Johnson (1993) Journal of the Optical Society of America A, 10, 2491-2521