79 lines
2.1 KiB
C
79 lines
2.1 KiB
C
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/* mpq_mul -- mutiply two rational numbers.
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Copyright (C) 1991 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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The GNU MP Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with the GNU MP Library; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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void
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#ifdef __STDC__
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mpq_mul (MP_RAT *prod, const MP_RAT *m1, const MP_RAT *m2)
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#else
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mpq_mul (prod, m1, m2)
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MP_RAT *prod;
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const MP_RAT *m1;
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const MP_RAT *m2;
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#endif
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{
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MP_INT gcd1, gcd2;
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MP_INT tmp1, tmp2;
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mpz_init (&gcd1);
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mpz_init (&gcd2);
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mpz_init (&tmp1);
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mpz_init (&tmp2);
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/* PROD might be identical to either operand, so don't store the
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result there until we are finished with the input operands. We
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dare to overwrite the numerator of PROD when we are finished
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with the numerators of M1 and M1. */
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mpz_gcd (&gcd1, &(m1->num), &(m2->den));
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mpz_gcd (&gcd2, &(m2->num), &(m1->den));
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if (gcd1.size > 1 || gcd1.d[0] != 1)
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mpz_div (&tmp1, &(m1->num), &gcd1);
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else
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mpz_set (&tmp1, &(m1->num));
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if (gcd2.size > 1 || gcd2.d[0] != 1)
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mpz_div (&tmp2, &(m2->num), &gcd2);
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else
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mpz_set (&tmp2, &(m2->num));
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mpz_mul (&(prod->num), &tmp1, &tmp2);
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if (gcd1.size > 1 || gcd1.d[0] != 1)
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mpz_div (&tmp1, &(m2->den), &gcd1);
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else
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mpz_set (&tmp1, &(m2->den));
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if (gcd2.size > 1 || gcd2.d[0] != 1)
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mpz_div (&tmp2, &(m1->den), &gcd2);
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else
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mpz_set (&tmp2, &(m1->den));
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mpz_mul (&(prod->den), &tmp1, &tmp2);
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mpz_clear (&tmp2);
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mpz_clear (&tmp1);
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mpz_clear (&gcd2);
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mpz_clear (&gcd1);
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}
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