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