spielwiese
Last change
on this file since 86aa4d5 was
a8af6a8,
checked in by Martin Lee <martinlee84@…>, 12 years ago
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chg: new command igcd to compute integer gcd
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-
Property mode set to
100644
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File size:
1.0 KB
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1 | /* emacs edit mode for this file is -*- C++ -*- */ |
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2 | /* $Id$ */ |
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3 | |
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4 | //{{{ docu |
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5 | // |
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6 | // cf_util.cc - miscellaneous functions, not necessarily related |
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7 | // to canonical forms. |
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8 | // |
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9 | // Used by: fac_cantzass.cc, gfops.cc |
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10 | // |
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11 | //}}} |
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12 | |
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13 | #include "config.h" |
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14 | |
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15 | //{{{ int ipower ( int b, int m ) |
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16 | //{{{ docu |
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17 | // |
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18 | // ipower() - calculate b^m in standard integer arithmetic. |
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19 | // |
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20 | // Note: Beware of overflows. |
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21 | // |
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22 | //}}} |
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23 | int ipower ( int b, int m ) |
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24 | { |
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25 | int prod = 1; |
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26 | |
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27 | while ( m != 0 ) |
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28 | { |
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29 | if ( m % 2 != 0 ) |
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30 | prod *= b; |
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31 | m /= 2; |
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32 | if ( m != 0 ) |
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33 | b *= b; |
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34 | } |
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35 | return prod; |
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36 | } |
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37 | //}}} |
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38 | |
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39 | int ilog2 (int a) |
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40 | { |
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41 | int n = -1; |
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42 | while ( a > 0 ) |
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43 | { |
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44 | n++; |
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45 | a /=2; |
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46 | } |
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47 | return n; |
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48 | } |
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49 | |
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50 | int igcd( int a, int b ) |
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51 | { |
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52 | if ( a < 0 ) a = -a; |
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53 | if ( b < 0 ) b = -b; |
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54 | |
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55 | int c; |
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56 | |
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57 | while ( b != 0 ) |
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58 | { |
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59 | c = a % b; |
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60 | a = b; |
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61 | b = c; |
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62 | } |
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63 | return a; |
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64 | } |
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65 | |
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66 | #include<stdio.h> |
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67 | #include<stdlib.h> |
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68 | |
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69 | void factoryError_intern(const char *s) |
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70 | { |
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71 | fputs(s,stderr); |
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72 | abort(); |
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73 | } |
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74 | void (*factoryError)(const char *s) = factoryError_intern; |
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75 | |
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76 | |
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