Ignore:
Timestamp:
Jul 23, 2012, 5:29:18 PM (11 years ago)
Author:
Oleksandr Motsak <motsak@…>
Branches:
(u'jengelh-datetime', 'ceac47cbc86fe4a15902392bdbb9bd2ae0ea02c6')(u'spielwiese', '2234726c50d679d6664181a5c72f75a6fd64a787')
Children:
6779bb431ba1eced98b7cb0e1fed5fbfef1f0244
Parents:
98223c2d11013c57837511c1adb1ef9a16193b3d
git-author:
Oleksandr Motsak <motsak@mathematik.uni-kl.de>2012-07-23 17:29:18+02:00
git-committer:
Oleksandr Motsak <motsak@mathematik.uni-kl.de>2012-07-25 15:25:07+02:00
Message:
moved the definition of p_GetShortExpVector(poly, ring) to p_polys.cc
File:
1 edited

Legend:

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Removed

  • libpolys/polys/monomials/monomials.cc

    r98223c rf3094a  
    3030#endif
    3131
    32 #include <polys/monomials/ring.h>
    33 #include <reporter/reporter.h>
    34 #include <coeffs/numbers.h>
    35 #include <polys/monomials/ring.h>
    36 #include <polys/monomials/p_polys.h>
    37 #include <reporter/reporter.h>
    38 
    39 #ifdef PDEBUG
    40 int pDBsyzComp=0;
    41 #endif
    42 
    43 /***************************************************************
    44  *
    45  * Storage Managament Routines
    46  *
    47  ***************************************************************/
    48 
    49 
    50 static inline unsigned long GetBitFields(long e,
    51                                          unsigned int s, unsigned int n)
    52 {
    53 #define Sy_bit_L(x)     (((unsigned long)1L)<<(x))
    54   unsigned int i = 0;
    55   unsigned long  ev = 0L;
    56   assume(n > 0 && s < BIT_SIZEOF_LONG);
    57   do
    58   {
    59     assume(s+i < BIT_SIZEOF_LONG);
    60     if (e > (long) i) ev |= Sy_bit_L(s+i);
    61     else break;
    62     i++;
    63   }
    64   while (i < n);
    65   return ev;
    66 }
    67 
    68 // Short Exponent Vectors are used for fast divisibility tests
    69 // ShortExpVectors "squeeze" an exponent vector into one word as follows:
    70 // Let n = BIT_SIZEOF_LONG / pVariables.
    71 // If n == 0 (i.e. pVariables > BIT_SIZE_OF_LONG), let m == the number
    72 // of non-zero exponents. If (m>BIT_SIZEOF_LONG), then sev = ~0, else
    73 // first m bits of sev are set to 1.
    74 // Otherwise (i.e. pVariables <= BIT_SIZE_OF_LONG)
    75 // represented by a bit-field of length n (resp. n+1 for some
    76 // exponents). If the value of an exponent is greater or equal to n, then
    77 // all of its respective n bits are set to 1. If the value of an exponent
    78 // is smaller than n, say m, then only the first m bits of the respective
    79 // n bits are set to 1, the others are set to 0.
    80 // This way, we have:
    81 // exp1 / exp2 ==> (ev1 & ~ev2) == 0, i.e.,
    82 // if (ev1 & ~ev2) then exp1 does not divide exp2
    83 unsigned long p_GetShortExpVector(poly p, const ring r)
    84 {
    85   assume(p != NULL);
    86   if (p == NULL) return 0;
    87   unsigned long ev = 0; // short exponent vector
    88   unsigned int n = BIT_SIZEOF_LONG / r->N; // number of bits per exp
    89   unsigned int m1; // highest bit which is filled with (n+1)
    90   unsigned int i = 0, j=1;
    91 
    92   if (n == 0)
    93   {
    94     if (r->N <2*BIT_SIZEOF_LONG)
    95     {
    96       n=1;
    97       m1=0;
    98     }
    99     else
    100     {
    101       for (; j<=(unsigned long) r->N; j++)
    102       {
    103         if (p_GetExp(p,j,r) > 0) i++;
    104         if (i == BIT_SIZEOF_LONG) break;
    105       }
    106       if (i>0)
    107       ev = ~((unsigned long)0) >> ((unsigned long) (BIT_SIZEOF_LONG - i));
    108       return ev;
    109     }
    110   }
    111   else
    112   {
    113     m1 = (n+1)*(BIT_SIZEOF_LONG - n*r->N);
    114   }
    115 
    116   n++;
    117   while (i<m1)
    118   {
    119     ev |= GetBitFields(p_GetExp(p, j,r), i, n);
    120     i += n;
    121     j++;
    122   }
    123 
    124   n--;
    125   while (i<BIT_SIZEOF_LONG)
    126   {
    127     ev |= GetBitFields(p_GetExp(p, j,r), i, n);
    128     i += n;
    129     j++;
    130   }
    131   return ev;
    132 }
    13332
    13433#endif // POLYS_IMPL_CC
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