lasq5 - lasq5: dqds step

Generated automatically by Doxygen for LAPACK from the source code. Version 3.12.0 Sun Jul 20 2025 01:40:05 lasq5(3)

subroutinedlasq5(integeri0,integern0,doubleprecision,dimension(*)z,integerpp,doubleprecisiontau,doubleprecisionsigma,doubleprecisiondmin,doubleprecisiondmin1,doubleprecisiondmin2,doubleprecisiondn,doubleprecisiondnm1,doubleprecisiondnm2,logicalieee,doubleprecisioneps)DLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr. Purpose: DLASQ5 computes one dqds transform in ping-pong form, one version for IEEE machines another for non IEEE machines. ParametersI0 I0 is INTEGER First index. N0 N0 is INTEGER Last index. Z Z is DOUBLE PRECISION array, dimension ( 4*N ) Z holds the qd array. EMIN is stored in Z(4*N0) to avoid an extra argument. PP PP is INTEGER PP=0 for ping, PP=1 for pong. TAU TAU is DOUBLE PRECISION This is the shift. SIGMA SIGMA is DOUBLE PRECISION This is the accumulated shift up to this step. DMIN DMIN is DOUBLE PRECISION Minimum value of d. DMIN1 DMIN1 is DOUBLE PRECISION Minimum value of d, excluding D( N0 ). DMIN2 DMIN2 is DOUBLE PRECISION Minimum value of d, excluding D( N0 ) and D( N0-1 ). DN DN is DOUBLE PRECISION d(N0), the last value of d. DNM1 DNM1 is DOUBLE PRECISION d(N0-1). DNM2 DNM2 is DOUBLE PRECISION d(N0-2). IEEE IEEE is LOGICAL Flag for IEEE or non IEEE arithmetic. EPS EPS is DOUBLE PRECISION This is the value of epsilon used. Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. subroutineslasq5(integeri0,integern0,real,dimension(*)z,integerpp,realtau,realsigma,realdmin,realdmin1,realdmin2,realdn,realdnm1,realdnm2,logicalieee,realeps)SLASQ5computesonedqdstransforminping-pongform.Usedbysbdsqrandsstegr.Purpose: SLASQ5 computes one dqds transform in ping-pong form, one version for IEEE machines another for non IEEE machines. ParametersI0 I0 is INTEGER First index. N0 N0 is INTEGER Last index. Z Z is REAL array, dimension ( 4*N ) Z holds the qd array. EMIN is stored in Z(4*N0) to avoid an extra argument. PP PP is INTEGER PP=0 for ping, PP=1 for pong. TAU TAU is REAL This is the shift. SIGMA SIGMA is REAL This is the accumulated shift up to this step. DMIN DMIN is REAL Minimum value of d. DMIN1 DMIN1 is REAL Minimum value of d, excluding D( N0 ). DMIN2 DMIN2 is REAL Minimum value of d, excluding D( N0 ) and D( N0-1 ). DN DN is REAL d(N0), the last value of d. DNM1 DNM1 is REAL d(N0-1). DNM2 DNM2 is REAL d(N0-2). IEEE IEEE is LOGICAL Flag for IEEE or non IEEE arithmetic. EPS EPS is REAL This is the value of epsilon used. Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd.

lasq5 - lasq5: dqds step

Functions subroutine dlasq5 (i0, n0, z, pp, tau, sigma, dmin, dmin1, dmin2, dn, dnm1, dnm2, ieee, eps) DLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr. subroutine slasq5 (i0, n0, z, pp, tau, sigma, dmin, dmin1, dmin2, dn, dnm1, dnm2, ieee, eps) SLASQ5computesonedqdstransforminping-pongform.Usedbysbdsqrandsstegr.