.TH "SRC/ssyequb.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*- .ad l .nh .SH NAME SRC/ssyequb.f .SH SYNOPSIS .br .PP .SS "Functions/Subroutines" .in +1c .ti -1c .RI "subroutine \fBssyequb\fP (uplo, n, a, lda, s, scond, amax, work, info)" .br .RI "\fBSSYEQUB\fP " .in -1c .SH "Function/Subroutine Documentation" .PP .SS "subroutine ssyequb (character uplo, integer n, real, dimension( lda, * ) a, integer lda, real, dimension( * ) s, real scond, real amax, real, dimension( * ) work, integer info)" .PP \fBSSYEQUB\fP .PP \fBPurpose:\fP .RS 4 .PP .nf !> !> SSYEQUB computes row and column scalings intended to equilibrate a !> symmetric matrix A (with respect to the Euclidean norm) and reduce !> its condition number\&. The scale factors S are computed by the BIN !> algorithm (see references) so that the scaled matrix B with elements !> B(i,j) = S(i)*A(i,j)*S(j) has a condition number within a factor N of !> the smallest possible condition number over all possible diagonal !> scalings\&. !> .fi .PP .RE .PP \fBParameters\fP .RS 4 \fIUPLO\fP .PP .nf !> UPLO is CHARACTER*1 !> = 'U': Upper triangle of A is stored; !> = 'L': Lower triangle of A is stored\&. !> .fi .PP .br \fIN\fP .PP .nf !> N is INTEGER !> The order of the matrix A\&. N >= 0\&. !> .fi .PP .br \fIA\fP .PP .nf !> A is REAL array, dimension (LDA,N) !> The N-by-N symmetric matrix whose scaling factors are to be !> computed\&. !> .fi .PP .br \fILDA\fP .PP .nf !> LDA is INTEGER !> The leading dimension of the array A\&. LDA >= max(1,N)\&. !> .fi .PP .br \fIS\fP .PP .nf !> S is REAL array, dimension (N) !> If INFO = 0, S contains the scale factors for A\&. !> .fi .PP .br \fISCOND\fP .PP .nf !> SCOND is REAL !> If INFO = 0, S contains the ratio of the smallest S(i) to !> the largest S(i)\&. If SCOND >= 0\&.1 and AMAX is neither too !> large nor too small, it is not worth scaling by S\&. !> .fi .PP .br \fIAMAX\fP .PP .nf !> AMAX is REAL !> Largest absolute value of any matrix element\&. If AMAX is !> very close to overflow or very close to underflow, the !> matrix should be scaled\&. !> .fi .PP .br \fIWORK\fP .PP .nf !> WORK is REAL array, dimension (2*N) !> .fi .PP .br \fIINFO\fP .PP .nf !> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument had an illegal value !> > 0: if INFO = i, the i-th diagonal element is nonpositive\&. !> .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 \fBReferences:\fP .RS 4 Livne, O\&.E\&. and Golub, G\&.H\&., "Scaling by Binormalization", .br Numerical Algorithms, vol\&. 35, no\&. 1, pp\&. 97-120, January 2004\&. .br DOI 10\&.1023/B:NUMA\&.0000016606\&.32820\&.69 .br Tech report version: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.3.1679 .RE .PP .PP Definition at line \fB130\fP of file \fBssyequb\&.f\fP\&. .SH "Author" .PP Generated automatically by Doxygen for LAPACK from the source code\&.