potential bug in the manual

[Torbjorn Granlund]

Paul.Zimmermann at loria.fr (Paul Zimmermann) writes:

   - Function: mp_limb_t mpn_submul_1 (mp_limb_t *RP, const mp_limb_t
            *S1P, mp_size_t N, mp_limb_t S2LIMB)
       Multiply {S1P, N} and S2LIMB, and subtract the N least significant
       limbs of the product from {RP, N} and write the result to RP.
       Return the most significant limb of the product, minus borrow-out
       from the subtraction.                            ^^^^^^^^^^^^^^^^
  
  It seems to me it should be "plus borrow-out from the subtraction" instead.
  Indeed, if the N least significant limbs of the product {S1P, N} * S2LIMB are
  larger than {RP, N}, then the limb-borrow is C+1, where I denote C the most
  significant limb of {S1P, N} * S2LIMB.
  
You're right.  This error has been around since GMP 2.0, i.e., from
when mpn_submul_1 was first documented.

-- 
Torbjörn