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ocaml: phase 5.1 pow_mod.ml baseline (modular exponentiation, sum = 738639)
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Fast exponentiation by squaring with modular reduction:

  let rec pow_mod base exp m =
    if exp = 0 then 1
    else if exp mod 2 = 0 then
      let half = pow_mod base (exp / 2) m in
      (half * half) mod m
    else
      (base * pow_mod base (exp - 1) m) mod m

Even exponent halves and squares (O(log n)); odd decrements and
multiplies. mod-reduction at each step keeps intermediates bounded.

  pow_mod 2 30 1000003 + pow_mod 3 20 13 + pow_mod 5 17 100 = 738639

84 baseline programs total.
This commit is contained in:
giles
2026-05-09 17:15:47 +00:00
parent 2e84492d96
commit b6e723fc3e
3 changed files with 23 additions and 0 deletions
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11
lib/ocaml/baseline/pow_mod.ml Normal file
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let rec pow_mod base exp m =
if exp = 0 then 1
else if exp mod 2 = 0 then
let half = pow_mod base (exp / 2) m in
(half * half) mod m
else
(base * pow_mod base (exp - 1) m) mod m
;;
pow_mod 2 30 1000003 + pow_mod 3 20 13 + pow_mod 5 17 100