slaic1 (l)  Linux Man Pages
slaic1: applies one step of incremental condition estimation in its simplest version
NAME
SLAIC1  applies one step of incremental condition estimation in its simplest versionSYNOPSIS
 SUBROUTINE SLAIC1(
 JOB, J, X, SEST, W, GAMMA, SESTPR, S, C )
 INTEGER J, JOB
 REAL C, GAMMA, S, SEST, SESTPR
 REAL W( J ), X( J )
PURPOSE
SLAIC1 applies one step of incremental condition estimation in its simplest version: Let x, twonorm(x) = 1, be an approximate singular vector of an jbyj lower triangular matrix L, such thatThen SLAIC1 computes sestpr, s, c such that
the vector
is an approximate singular vector of
in the sense that
Depending on JOB, an estimate for the largest or smallest singular value is computed.
Note that [s c]aq and sestpr**2 is an eigenpair of the system
where alpha = xaq*w.
ARGUMENTS
 JOB (input) INTEGER

= 1: an estimate for the largest singular value is computed.
= 2: an estimate for the smallest singular value is computed.  J (input) INTEGER
 Length of X and W
 X (input) REAL array, dimension (J)
 The jvector x.
 SEST (input) REAL
 Estimated singular value of j by j matrix L
 W (input) REAL array, dimension (J)
 The jvector w.
 GAMMA (input) REAL
 The diagonal element gamma.
 SESTPR (output) REAL
 Estimated singular value of (j+1) by (j+1) matrix Lhat.
 S (output) REAL
 Sine needed in forming xhat.
 C (output) REAL

Cosine needed in forming xhat.