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Reference manual
A.4
PIM CGEV
PIM CGEV
Purpose
Solves the system Q1AQ2 x = Q1b using the CG method; returns, at each iteration, the estimates
of the smallest and largest eigenvalues of Q1 AQ2 derived from the associated Lanczos tridiagonal
matrix.
Synopsis
PIMSCGEV(X,B,WRK,IPAR,SPAR,MATVEC,PRECONL,PRECONR,PSSUM,PSNRM,PROGRESS)
PIMDCGEV(X,B,WRK,IPAR,DPAR,MATVEC,PRECONL,PRECONR,PDSUM,PDNRM,PROGRESS)
Storage requirements
Parameter No. of words
X, B
WRK
IPAR
PAR
IPAR(4)
6*IPAR(4)+2*IPAR(10)+1
13
4
Possible exit status values returned by IPAR(12): 0 -1 -3 -4 -8 -9 -10 -11
Function dependencies
BLAS COPY, AXPY,
LIBPIM
DOT
Notes
If more accuracy is required in the computation of the estimates of the eigenvalues, the
user may modify the value of the maximum number of iterations allowed in the routine
BISECTION (les pim22/single/src/pimscgev.f or pim22/double/src/pimdcgev.f).
Not available in COMPLEX or DOUBLE COMPLEX versions.
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