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https://github.com/vale981/arb
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48 lines
1.1 KiB
C
48 lines
1.1 KiB
C
/*
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Copyright (C) 2016 Fredrik Johansson
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This file is part of Arb.
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Arb is free software: you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License (LGPL) as published
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by the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version. See <http://www.gnu.org/licenses/>.
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*/
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#include "mag.h"
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#include "arf.h"
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void
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mag_sub(mag_t z, const mag_t x, const mag_t y)
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{
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if (mag_is_special(x) || mag_is_special(y))
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{
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if (mag_is_inf(x))
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mag_inf(z);
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else if (mag_is_inf(y))
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mag_zero(z);
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else
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mag_set(z, x); /* x - 0 = x; max(0 - y, 0) = 0 */
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}
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else
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{
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/* this should eventually have a proper implementation... */
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arf_t t, u;
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arf_init(t);
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arf_init(u);
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arf_set_mag(t, x);
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arf_set_mag(u, y);
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arf_sub(t, t, u, MAG_BITS, ARF_RND_UP);
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if (arf_sgn(t) >= 0)
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arf_get_mag(z, t);
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else
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mag_zero(z);
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arf_clear(t);
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arf_clear(u);
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}
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}
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