lasq6 - lasq6: dqds step

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subroutinedlasq6(integeri0,integern0,doubleprecision,dimension(*)z,integerpp,doubleprecisiondmin,doubleprecisiondmin1,doubleprecisiondmin2,doubleprecisiondn,doubleprecisiondnm1,doubleprecisiondnm2)DLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr. Purpose: DLASQ6 computes one dqd (shift equal to zero) transform in ping-pong form, with protection against underflow and overflow. 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. 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). Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. subroutineslasq6(integeri0,integern0,real,dimension(*)z,integerpp,realdmin,realdmin1,realdmin2,realdn,realdnm1,realdnm2)SLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr. Purpose: SLASQ6 computes one dqd (shift equal to zero) transform in ping-pong form, with protection against underflow and overflow. 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. 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). Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd.

lasq6 - lasq6: dqds step

Functions subroutine dlasq6 (i0, n0, z, pp, dmin, dmin1, dmin2, dn, dnm1, dnm2) DLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr. subroutine slasq6 (i0, n0, z, pp, dmin, dmin1, dmin2, dn, dnm1, dnm2) SLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.