Vega FEM Library (v1.1) User's Manual - University of Southern ...

SparseMatrixOutline(int n, double diagonal)
SparseMatrixOutline(int n, double * diagonal)
Sets the number of rows in the matrix, and optionally a starting value for all the diagonal entries or an
array of starting values for the diagonals.
SparseMatrixOutline(char * filename, int expand=1)
Constructs the outline from a file. For expand greater than 1, expands each element to a diagonal block
of size expand by expand. This is useful, for example, with mass matrices.
void AddEntry(int i, int j, double value=0.0)
void AddBlock3x3Entry(int i, int j, double * matrix3x3)
void AddBlockMatrix(int i, int j, const SparseMatrix * block, double scalarFactor=1.0)
Adds a value (or a matrix of values) starting at row i, column j. “Add” in this context means addition,
not insertion; if the position in the matrix is already non-zero, this new value is added to the existing value.
scalarFactor is multiplied with the block matrix values before they are added.
double GetEntry(int i, int j)
Gets the matrix value at row i, column j, or zero if the position has not been set.
class SparseMatrix A matrix storage class optimized for the case of the matrix having few non-zero
elements, i.e., a sparse matrix. The class uses row-based sparse storage. Each matrix row is stored as a list
of non-zero column positions and the corresponding entries. The class can perform matrix arithmetic, as
well as many other operations such as assigning submatrices or removing matrix rows and columns. It is
constructed by first specifying the locations of non-zero entries using the SparseMatrixOutline class. Once
this is finalized, one can initialize SparseMatrix, which writes the row elements into a linear array for fast
subsequent access. The sparsity pattern cannot be changed by SparseMatrix.
SparseMatrix(SparseMatrixOutline * sparseMatrixOutline)
SparseMatrix(const SparseMatrix & source)
SparseMatrix(char * filename)
Initializes the matrix values from a SparseMatrixOutline, another SparseMatrix, or a file.
int Save(char * filename, int oneIndexed=0)
Saves the matrix to disk. Returns 1 on error, 0 otherwise.
void SetEntry(int row, int j, double value)
void AddEntry(int row, int j, double value)
void GetEntry(int row, int j)
Sets, adds to, or gets the value in the jth non-zero element of row row of the matrix.
int GetRowLength(int row)
Returns the number of non-zero elements in the row.
int GetColumnIndex(int row, int j)
Returns the column index of the jth non-zero element in row row.
SparseMatrix operator+(const SparseMatrix & mat2)
SparseMatrix operator-(const SparseMatrix & mat2)
Returns a SparseMatrix equal to the sum of this matrix and SparseMatrix mat2. These two matrices
must have the same pattern of non-zero entries.
void MultiplyMatrix(int numDenseRows, int numDenseColumns, const double * denseMatrix,
double * result)
31