.TH "lasq4" 3 "Wed Feb 7 2024 11:30:40" "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
lasq4 \- lasq4: dqds step
.SH SYNOPSIS
.br
.PP
.SS "Functions"

.in +1c
.ti -1c
.RI "subroutine \fBdlasq4\fP (i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g)"
.br
.RI "\fBDLASQ4\fP computes an approximation to the smallest eigenvalue using values of d from the previous transform\&. Used by sbdsqr\&. "
.ti -1c
.RI "subroutine \fBslasq4\fP (i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g)"
.br
.RI "\fBSLASQ4\fP computes an approximation to the smallest eigenvalue using values of d from the previous transform\&. Used by sbdsqr\&. "
.in -1c
.SH "Detailed Description"
.PP 

.SH "Function Documentation"
.PP 
.SS "subroutine dlasq4 (integer i0, integer n0, double precision, dimension( * ) z, integer pp, integer n0in, double precision dmin, double precision dmin1, double precision dmin2, double precision dn, double precision dn1, double precision dn2, double precision tau, integer ttype, double precision g)"

.PP
\fBDLASQ4\fP computes an approximation to the smallest eigenvalue using values of d from the previous transform\&. Used by sbdsqr\&.  
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
 DLASQ4 computes an approximation TAU to the smallest eigenvalue
 using values of d from the previous transform\&.
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fII0\fP 
.PP
.nf
          I0 is INTEGER
        First index\&.
.fi
.PP
.br
\fIN0\fP 
.PP
.nf
          N0 is INTEGER
        Last index\&.
.fi
.PP
.br
\fIZ\fP 
.PP
.nf
          Z is DOUBLE PRECISION array, dimension ( 4*N0 )
        Z holds the qd array\&.
.fi
.PP
.br
\fIPP\fP 
.PP
.nf
          PP is INTEGER
        PP=0 for ping, PP=1 for pong\&.
.fi
.PP
.br
\fIN0IN\fP 
.PP
.nf
          N0IN is INTEGER
        The value of N0 at start of EIGTEST\&.
.fi
.PP
.br
\fIDMIN\fP 
.PP
.nf
          DMIN is DOUBLE PRECISION
        Minimum value of d\&.
.fi
.PP
.br
\fIDMIN1\fP 
.PP
.nf
          DMIN1 is DOUBLE PRECISION
        Minimum value of d, excluding D( N0 )\&.
.fi
.PP
.br
\fIDMIN2\fP 
.PP
.nf
          DMIN2 is DOUBLE PRECISION
        Minimum value of d, excluding D( N0 ) and D( N0-1 )\&.
.fi
.PP
.br
\fIDN\fP 
.PP
.nf
          DN is DOUBLE PRECISION
        d(N)
.fi
.PP
.br
\fIDN1\fP 
.PP
.nf
          DN1 is DOUBLE PRECISION
        d(N-1)
.fi
.PP
.br
\fIDN2\fP 
.PP
.nf
          DN2 is DOUBLE PRECISION
        d(N-2)
.fi
.PP
.br
\fITAU\fP 
.PP
.nf
          TAU is DOUBLE PRECISION
        This is the shift\&.
.fi
.PP
.br
\fITTYPE\fP 
.PP
.nf
          TTYPE is INTEGER
        Shift type\&.
.fi
.PP
.br
\fIG\fP 
.PP
.nf
          G is DOUBLE PRECISION
        G is passed as an argument in order to save its value between
        calls to DLASQ4\&.
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 
.PP
Univ\&. of California Berkeley 
.PP
Univ\&. of Colorado Denver 
.PP
NAG Ltd\&. 
.RE
.PP
\fBFurther Details:\fP
.RS 4

.PP
.nf
  CNST1 = 9/16
.fi
.PP
 
.RE
.PP

.SS "subroutine slasq4 (integer i0, integer n0, real, dimension( * ) z, integer pp, integer n0in, real dmin, real dmin1, real dmin2, real dn, real dn1, real dn2, real tau, integer ttype, real g)"

.PP
\fBSLASQ4\fP computes an approximation to the smallest eigenvalue using values of d from the previous transform\&. Used by sbdsqr\&.  
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
 SLASQ4 computes an approximation TAU to the smallest eigenvalue
 using values of d from the previous transform\&.
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fII0\fP 
.PP
.nf
          I0 is INTEGER
        First index\&.
.fi
.PP
.br
\fIN0\fP 
.PP
.nf
          N0 is INTEGER
        Last index\&.
.fi
.PP
.br
\fIZ\fP 
.PP
.nf
          Z is REAL array, dimension ( 4*N0 )
        Z holds the qd array\&.
.fi
.PP
.br
\fIPP\fP 
.PP
.nf
          PP is INTEGER
        PP=0 for ping, PP=1 for pong\&.
.fi
.PP
.br
\fIN0IN\fP 
.PP
.nf
          N0IN is INTEGER
        The value of N0 at start of EIGTEST\&.
.fi
.PP
.br
\fIDMIN\fP 
.PP
.nf
          DMIN is REAL
        Minimum value of d\&.
.fi
.PP
.br
\fIDMIN1\fP 
.PP
.nf
          DMIN1 is REAL
        Minimum value of d, excluding D( N0 )\&.
.fi
.PP
.br
\fIDMIN2\fP 
.PP
.nf
          DMIN2 is REAL
        Minimum value of d, excluding D( N0 ) and D( N0-1 )\&.
.fi
.PP
.br
\fIDN\fP 
.PP
.nf
          DN is REAL
        d(N)
.fi
.PP
.br
\fIDN1\fP 
.PP
.nf
          DN1 is REAL
        d(N-1)
.fi
.PP
.br
\fIDN2\fP 
.PP
.nf
          DN2 is REAL
        d(N-2)
.fi
.PP
.br
\fITAU\fP 
.PP
.nf
          TAU is REAL
        This is the shift\&.
.fi
.PP
.br
\fITTYPE\fP 
.PP
.nf
          TTYPE is INTEGER
        Shift type\&.
.fi
.PP
.br
\fIG\fP 
.PP
.nf
          G is REAL
        G is passed as an argument in order to save its value between
        calls to SLASQ4\&.
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 
.PP
Univ\&. of California Berkeley 
.PP
Univ\&. of Colorado Denver 
.PP
NAG Ltd\&. 
.RE
.PP
\fBFurther Details:\fP
.RS 4

.PP
.nf
  CNST1 = 9/16
.fi
.PP
 
.RE
.PP

.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.