 
  
  
  
  
 
This section contains performance numbers for selected driver routines. These routines provide complete solutions for common linear algebra problems.
 
 ) for selected ScaLAPACK drivers for matrices
of order N.  Approximate values of the constants
) for selected ScaLAPACK drivers for matrices
of order N.  Approximate values of the constants
 and
 and  defined in section 5.2.3
are also provided.
 defined in section 5.2.3
are also provided.
  
Table 5.8: ``Standard'' floating-point operation ( ) and communication
          costs (
) and communication
          costs ( ,
,  ) for selected ScaLAPACK drivers
) for selected ScaLAPACK drivers
The operation counts given for the eigenvalue and SVD drivers
are incomplete.  They do not include any of the  computation
costs (i.e., the entire tridiagonal eigendecomposition is ignored in 
PxxxEVX).  Furthermore, the reductions involved require matrix-vector
multiplies, which are less efficient than the matrix-matrix multiplies
required by the other drivers listed here.
Hence this table greatly underestimates the execution time
of the eigenvalue and SVD drivers, especially the expert symmetric eigensolver drivers.
For PxLAHQR, when only eigenvalues are computed,
 computation
costs (i.e., the entire tridiagonal eigendecomposition is ignored in 
PxxxEVX).  Furthermore, the reductions involved require matrix-vector
multiplies, which are less efficient than the matrix-matrix multiplies
required by the other drivers listed here.
Hence this table greatly underestimates the execution time
of the eigenvalue and SVD drivers, especially the expert symmetric eigensolver drivers.
For PxLAHQR, when only eigenvalues are computed,  and
 and  look the same as the full Schur form case, in terms of ``order of
magnitude''.  There is actually
look the same as the full Schur form case, in terms of ``order of
magnitude''.  There is actually  to
 to  the
number of messages/volume depending on the circumstances.
 the
number of messages/volume depending on the circumstances.
 
  
  
  
 