To any and all:
To whoever can assist:

I am presently in discussion relating to the rotational speed of the Sun.
Two formulas were recently introduced into the conversation.

The first formula:

Rotation rate = 2.951 - (0.351(+/-0.03)*sin2L + 0.443(+/-0.05)*sin4L)

Harvey, Howard and Forgach (1990).

The second formula:

Rotation rate = 14.37-(2.33sin2L + 1.56 sin4L) degrees/day.

Allen, from the 2nd ed, 1955.

Also see

Are both correct for given/specific criteria, or is there an error with one
of them.

Thank you in advance for any information you can provide.

Clive Ross