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/*
Copyright (C) 2010 Fredrik Johansson
Copyright (C) 2013 Mike Hansen
Copyright (C) 2021 Daniel Schultz
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "fmpz.h"
#include "fmpz_vec.h"
#include "fmpz_mod_mat.h"
void fmpz_mod_mat_randrank(fmpz_mod_mat_t mat, flint_rand_t state, slong rank, const fmpz_mod_ctx_t ctx)
{
slong i;
fmpz * diag;
if (rank < 0 || rank > fmpz_mod_mat_nrows(mat, ctx) || rank > fmpz_mod_mat_ncols(mat, ctx))
flint_throw(FLINT_ERROR, "Impossible rank in %s\n", __func__);
diag = _fmpz_vec_init(rank);
for (i = 0; i < rank; i++)
{
fmpz_randm(diag + i, state, ctx->n);
if (fmpz_is_zero(diag + i))
fmpz_one(diag + i);
}
fmpz_mat_randpermdiag(mat, state, diag, rank);
_fmpz_vec_clear(diag, rank);
}