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impl. powmod

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This commit is contained in:
Jiri Pittner 2023-12-29 23:03:56 +01:00
parent 40b23f19d6
commit f0325ba6f5
2 changed files with 28 additions and 0 deletions
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25
numbers.cc
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@ -117,6 +117,30 @@ return y;
} }
template <typename N>
N powmod(const N &x, N i, const N &m)
{
if(i==0) return 1;
if(i==1) return x%m;
N y,z;
z=x%m;
while(!(i&1))
{
z = (z*z)%m;
i >>= 1;
}
y=z;
while((i >>= 1)/*!=0*/)
{
z = (z*z)%m;
if(i&1) y = (y*z)%m;
}
return y;
}
//force instantization //force instantization
@ -126,6 +150,7 @@ template FACTORIZATION<N> factorization(const N &x); \
template N nextprime(N x); \ template N nextprime(N x); \
template std::ostream & operator<<(std::ostream &s, const FACTORIZATION<N> &x); \ template std::ostream & operator<<(std::ostream &s, const FACTORIZATION<N> &x); \
template N pow(const N &x, N i); \ template N pow(const N &x, N i); \
template N powmod(const N &x, N i, const N &m); \
template N eulerphi(const FACTORIZATION<N> &f); \ template N eulerphi(const FACTORIZATION<N> &f); \

3
numbers.h
View File

@ -62,6 +62,9 @@ N eulerphi(const N &x) {return eulerphi(factorization(x));}
template <typename N> template <typename N>
N pow(const N &x, N i); N pow(const N &x, N i);
template <typename N>
N powmod(const N &x, N i, const N &m);
}//namespace }//namespace
#endif #endif