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/*
Copyright (C) 2022 Fredrik Johansson
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 "gr.h"
#include "gr_mat.h"
int
gr_mat_trace(gr_ptr res, const gr_mat_t mat, gr_ctx_t ctx)
{
slong i, r, c;
slong sz = ctx->sizeof_elem;
int status = GR_SUCCESS;
r = mat->r;
c = mat->c;
if (r != c)
return GR_DOMAIN;
if (r == 0)
return gr_zero(res, ctx);
if (r == 1)
return gr_set(res, GR_MAT_ENTRY(mat, 0, 0, sz), ctx);
status |= gr_add(res, GR_MAT_ENTRY(mat, 0, 0, sz),
GR_MAT_ENTRY(mat, 1, 1, sz), ctx);
for (i = 2; i < r; i++)
status |= gr_add(res, res, GR_MAT_ENTRY(mat, i, i, sz), ctx);
return status;
}