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add a smart realloc algorithm when filling a sparse matrix

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This commit is contained in:
Gael Guennebaud
2009-01-18 18:00:19 +00:00
parent 0c7974dd4d
commit d58bb54e7f
3 changed files with 20 additions and 8 deletions
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21
Eigen/src/Sparse/SparseMatrix.h
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@@ -200,7 +200,21 @@ class SparseMatrix
int startId = m_outerIndex[outer];
int id = m_outerIndex[outer+1]-1;
++m_outerIndex[outer+1];
m_data.resize(id+2);
float reallocRatio = 1;
if (m_data.allocatedSize()<id+2)
{
// we need to reallocate the data, to reduce multiple reallocations
// we use a smart resize algorithm based on the current filling ratio
// we use float to avoid overflows
float nnzEstimate = float(m_outerIndex[outer])*float(m_outerSize)/float(outer);
reallocRatio = (nnzEstimate-float(m_data.size()))/float(m_data.size());
// let's bounds the realloc ratio to
// 1) reduce multiple minor realloc when the matrix is almost filled
// 2) avoid to allocate too much memory when the matrix is almost empty
reallocRatio = std::min(std::max(reallocRatio,1.5f),8.f);
}
m_data.resize(id+2,reallocRatio);
while ( (id >= startId) && (m_data.index(id) > inner) )
{
@@ -209,10 +223,7 @@ class SparseMatrix
--id;
}
m_data.index(id+1) = inner;
//return (m_data.value(id+1) = 0);
m_data.value(id+1) = 0;
// std::cerr << m_outerIndex[outer] << " " << m_outerIndex[outer+1] << "\n";
return m_data.value(id+1);
return (m_data.value(id+1) = 0);
}
// inline void