English
The IcoMod value can be expressed as a shift by a plus a fractional part times p, i.e., the fractional part of (b − a)/p scaled by p added to a.
Русский
Значение IcoMod выражается как сдвиг на a плюс дробная часть (b − a)/p, умноженная на p.
LaTeX
$$$$ \operatorname{toIcoMod}(hp, a, b) = a + \operatorname{fract}\left(\frac{b - a}{p}\right) \cdot p $$$$
Lean4
theorem toIcoMod_eq_add_fract_mul (a b : α) : toIcoMod hp a b = a + Int.fract ((b - a) / p) * p :=
by
rw [toIcoMod, toIcoDiv_eq_floor, Int.fract]
simp [field, -Int.self_sub_floor]
ring