h12.f
SUBROUTINE H12 (MODE, LPIVOT, L1, M, U, IUE, UP, C, ICE, ICV, NCV)
C***BEGIN PROLOGUE H12
....
....
Warning: this routine is not intended to be user-callable.
....
....
C***SUBSIDIARY
C***PURPOSE Subsidiary to HFTI, LSEI and WNNLS
C***LIBRARY SLATEC
C***TYPE SINGLE PRECISION (H12-S, DH12-D)
C***AUTHOR (UNKNOWN)
C***DESCRIPTION
C
C C.L.Lawson and R.J.Hanson, Jet Propulsion Laboratory, 1973 Jun 12
C to appear in 'Solving Least Squares Problems', Prentice-Hall, 1974
C
C Construction and/or application of a single
C Householder transformation.. Q = I + U*(U**T)/B
C
C MODE = 1 or 2 to select algorithm H1 or H2 .
C LPIVOT is the index of the pivot element.
C L1,M If L1 .LE. M the transformation will be constructed to
C zero elements indexed from L1 through M. If L1 GT. M
C THE SUBROUTINE DOES AN IDENTITY TRANSFORMATION.
C U(),IUE,UP On entry to H1 U() contains the pivot vector.
C IUE is the storage increment between elements.
C On exit from H1 U() and UP
C contain quantities defining the vector U of the
C Householder transformation. On entry to H2 U()
C and UP should contain quantities previously computed
C by H1. These will not be modified by H2.
C C() On entry to H1 or H2 C() contains a matrix which will be
C regarded as a set of vectors to which the Householder
C transformation is to be applied. On exit C() contains the
C set of transformed vectors.
C ICE Storage increment between elements of vectors in C().
C ICV Storage increment between vectors in C().
C NCV Number of vectors in C() to be transformed. If NCV .LE. 0
C no operations will be done on C().
C
C***SEE ALSO HFTI, LSEI, WNNLS
C***ROUTINES CALLED SAXPY, SDOT, SSWAP
C***REVISION HISTORY (YYMMDD)
C 790101 DATE WRITTEN
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890831 Modified array declarations. (WRB)
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900328 Added TYPE section. (WRB)
C***END PROLOGUE H12