I changed but the result are same as previous, since both are in same
size in my system I guess.
On Fri, Nov 23, 2012 at 3:14 PM, Bill Hart <goodwillh...@googlemail.com>wrote:
> One problem is that you are using unsigned int, instead of mp_limb_t
> (which is probably unsigned long or unsigned long long on your
> machine).
>
> Bill.
>
> On 23 November 2012 13:12, mgundes <mg...@hotmail.com> wrote:
> >
> > Hi Bill, thanks for reply.
> >
> > I run simple code below for different lengths of array muıltiplication
> > and I got weird results with gmp_printf(). I also printed c array and it
> > seems true but printed result is weird. What is wrong or missing in
> function
> > below?
> >
> > int main() {
> >
> > unsigned int a[4] = {100, 20, 30, 40};
> > unsigned int b[4] = {200, 10, 5, 120};
> > unsigned int c[8];
> >
> > memset(c, 0, 8 * sizeof(unsigned int));
> > mpn_mul((mp_limb_t *) c,
> > (mp_limb_t *) a, 1,
> > (mp_limb_t *) b, 1);
> >
> > for (int i=0; i<8; i++)
> > printf("c[%d]: %u\n", i, c[i]);
> > gmp_printf("\nresult: %Nu\n\n\n", c, 8);
> >
> >
> > memset(c, 0, 8 * sizeof(unsigned int));
> > mpn_mul((mp_limb_t *) c,
> > (mp_limb_t *) a, 2,
> > (mp_limb_t *) b, 3);
> >
> > for (int i=0; i<8; i++)
> > printf("c[%d]: %u\n", i, c[i]);
> > gmp_printf("\nresult: %Nu\n\n\n", c, 8);
> >
> > memset(c, 0, 8 * sizeof(unsigned int));
> > mpn_mul((mp_limb_t *) c,
> > (mp_limb_t *) a, 4,
> > (mp_limb_t *) b, 4);
> >
> > for (int i=0; i<8; i++)
> > printf("c[%d]: %u\n", i, c[i]);
> > gmp_printf("\nresult: %Nu\n\n\n", c, 8);
> >
> >
> > return 0;
> > }
> >
> > Kind Regards,
> > Thanks
> >
> > MahmutG
> >
> >
> > On Fri, Nov 23, 2012 at 3:09 AM, Bill Hart <goodwillh...@googlemail.com>
> > wrote:
> >>
> >> The result could be up to 8 limbs, which is why you should allocate 8
> >> limbs for c. The top limb might turn out to be zero of course.
> >>
> >> The easiest way to print the result is to use gmp_printf with the %N
> >> option for mpn's. You need to also give it the number of limbs, as
> >> documented on pages 67-68 of our documentation.
> >>
> >> Bill.
> >>
> >> On 23 November 2012 00:55, mgundes <mg...@hotmail.com> wrote:
> >> >
> >> > Hi,
> >> >
> >> > I am not good at arithmetic but I need to calculate multiplication of
> >> > big
> >> > numbers. I will try to explain my need:
> >> >
> >> > For instance, if I have two 128 bit numbers represented with arrays
> >> > below:
> >> >
> >> > unsigned int a[4] = {100, 20, 30, 40};
> >> > unsigned int b[4] = {200, 10, 5, 120};
> >> > unsigned int c[4] = {0,0,0,0};
> >> >
> >> > I want to multiply a and b, then assign the result to the c:
> >> >
> >> > mpn_mul_n((mp_limb_t *)c, (const mp_limb_t *)a, (const
> mp_limb_t
> >> > *)b,
> >> > 4);
> >> >
> >> > Since mpn_mul takes result pointer as mp_limb_t type, then what if
> >> > result
> >> > exceeds? I mean the result of two integer multiplication probably
> >> > exceeds
> >> > integer size. Is there any example for multiplication of big numbers?
> I
> >> > tried mpn_mul_n() as above and used mpn_get_str to see the result but
> >> > I
> >> > guess I could not use correctly.
> >> >
> >> > Kind regards,
> >> > Thanks
> >> >
> >> > --
> >> > MahmutG
> >> >
> >> > --
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> >>
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> >
> >
> >
> > --
> > MahmutG
> >
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