lasq4 - lasq4: dqds step

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subroutinedlasq4(integeri0,integern0,doubleprecision,dimension(*)z,integerpp,integern0in,doubleprecisiondmin,doubleprecisiondmin1,doubleprecisiondmin2,doubleprecisiondn,doubleprecisiondn1,doubleprecisiondn2,doubleprecisiontau,integerttype,doubleprecisiong)DLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr. Purpose: DLASQ4 computes an approximation TAU to the smallest eigenvalue using values of d from the previous transform. ParametersI0 I0 is INTEGER First index. N0 N0 is INTEGER Last index. Z Z is DOUBLE PRECISION array, dimension ( 4*N0 ) Z holds the qd array. PP PP is INTEGER PP=0 for ping, PP=1 for pong. N0IN N0IN is INTEGER The value of N0 at start of EIGTEST. 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(N) DN1 DN1 is DOUBLE PRECISION d(N-1) DN2 DN2 is DOUBLE PRECISION d(N-2) TAU TAU is DOUBLE PRECISION This is the shift. TTYPE TTYPE is INTEGER Shift type. G G is DOUBLE PRECISION G is passed as an argument in order to save its value between calls to DLASQ4. Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. FurtherDetails: CNST1 = 9/16 subroutineslasq4(integeri0,integern0,real,dimension(*)z,integerpp,integern0in,realdmin,realdmin1,realdmin2,realdn,realdn1,realdn2,realtau,integerttype,realg)SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr. Purpose: SLASQ4 computes an approximation TAU to the smallest eigenvalue using values of d from the previous transform. ParametersI0 I0 is INTEGER First index. N0 N0 is INTEGER Last index. Z Z is REAL array, dimension ( 4*N0 ) Z holds the qd array. PP PP is INTEGER PP=0 for ping, PP=1 for pong. N0IN N0IN is INTEGER The value of N0 at start of EIGTEST. 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(N) DN1 DN1 is REAL d(N-1) DN2 DN2 is REAL d(N-2) TAU TAU is REAL This is the shift. TTYPE TTYPE is INTEGER Shift type. G G is REAL G is passed as an argument in order to save its value between calls to SLASQ4. Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. FurtherDetails: CNST1 = 9/16

lasq4 - lasq4: dqds step

Functions subroutine dlasq4 (i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g) DLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr. subroutine slasq4 (i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g) SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.