Arbitrary precision modular matrix inverse in Julia

bigint_modinv.jl

using LinearAlgebra


function inverse(a::AbstractMatrix{BigInt}, modulus)
    m, n = size(a)
    if m - n != 0
        error("cannot find modular inverse of non-square matrix")
    end
    det_inv = invmod(BigInt(det(a)), modulus)
    if det_inv == 0
        error("cannot invert singular matrix")
    end
    cofactors = Matrix{BigInt}(undef, size(a))
    for i in 1:n
        for j in 1:n
            minor = det(view(a, setdiff(1:n, [i]), setdiff(1:n, [j])))
            cofactors[i, j] = mod(-1, modulus)^(i+j) * minor
        end
    end
    result = mod.(det_inv .* cofactors', modulus)
end