90 lines
2.0 KiB
Plaintext
90 lines
2.0 KiB
Plaintext
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@q $Id: tl_static.cweb 200 2005-05-12 12:28:19Z kamenik $ @>
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@q Copyright 2004, Ondra Kamenik @>
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@ Start of {\tt tl\_static.cpp} file.
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@c
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#include "tl_static.h"
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#include "tl_exception.h"
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TLStatic tls;
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@<|TLStatic| methods@>;
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@<|PascalTriangle| constructor code@>;
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@<|PascalTriangle::noverk| code@>;
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@ Note that we allow for repeated calls of |init|. This is not normal
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and the only purpose of allowing this is the test suite.
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@<|TLStatic| methods@>=
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TLStatic::TLStatic()
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{
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ebundle = NULL;
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pbundle = NULL;
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ptriang = NULL;
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}
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TLStatic::~TLStatic()
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{
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if (ebundle)
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delete ebundle;
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if (pbundle)
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delete pbundle;
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if (ptriang)
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delete ptriang;
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}
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void TLStatic::init(int dim, int nvar)
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{
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if (ebundle)
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ebundle->generateUpTo(dim);
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else
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ebundle = new EquivalenceBundle(dim);
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if (pbundle)
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pbundle->generateUpTo(dim);
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else
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pbundle = new PermutationBundle(dim);
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if (ptriang)
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delete ptriang;
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ptriang = new PascalTriangle(nvar, dim);
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}
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@ The coefficients are stored in |data| row by row where a row are
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coeffs with the same $k$.
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We first initialize the first row with ones. Then for each other row
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we initialize the first item to one, and other items are a sum of
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coefficients of $n-1$ which is in code |i+j-1|.
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@<|PascalTriangle| constructor code@>=
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PascalTriangle::PascalTriangle(int n, int k)
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: data(new int[(n+1)*(k+1)]), kmax(k), nmax(n)
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{
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for (int i = 0; i <= n; i++)
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data[i] = 1;
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for (int j = 1; j <= k; j++) {
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data[j*(nmax+1)] = 1;
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for (int i = 1; i <= n; i++)
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data[j*(nmax+1)+i] = noverk(i+j-1,j) + noverk(i+j-1,j-1);
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}
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}
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@ Clear. Recall, that there are |nmax+1| items in a row.
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@<|PascalTriangle::noverk| code@>=
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int PascalTriangle::noverk(int n, int k) const
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{
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TL_RAISE_IF(k > n || n < 0,
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"Wrong arguments for PascalTriangle::noverk");
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if (k <= kmax && n-k <= nmax)
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return data[k*(nmax+1)+n-k];
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if (n-k <= kmax && k <= nmax)
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return data[(n-k)*(nmax+1)+k];
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TL_RAISE("n or k out of range in PascalTriangle::noverk");
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return 0;
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}
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@ End of {\tt tl\_static.cpp} file.
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