.TH DSPR 1 "November 2008" "BLAS routine" "BLAS routine" .SH NAME DSPR - performs the symmetric rank 1 operation A := alpha*x*x\(aq + A, .SH SYNOPSIS .TP 40 SUBROUTINE DSPR(UPLO,N,ALPHA,X,INCX,AP) .TP 40 .ti +4 DOUBLE PRECISION ALPHA .TP 40 .ti +4 INTEGER INCX,N .TP 40 .ti +4 CHARACTER UPLO .TP 40 .ti +4 DOUBLE PRECISION AP(*),X(*) .SH PURPOSE DSPR performs the symmetric rank 1 operation where alpha is a real scalar, x is an n element vector and A is an n by n symmetric matrix, supplied in packed form. .br .SH ARGUMENTS .TP 7 UPLO - CHARACTER*1. On entry, UPLO specifies whether the upper or lower triangular part of the matrix A is supplied in the packed array AP as follows: UPLO = \(aqU\(aq or \(aqu\(aq The upper triangular part of A is supplied in AP. UPLO = \(aqL\(aq or \(aql\(aq The lower triangular part of A is supplied in AP. Unchanged on exit. .TP 7 N - INTEGER. On entry, N specifies the order of the matrix A. N must be at least zero. Unchanged on exit. .TP 7 ALPHA - DOUBLE PRECISION. On entry, ALPHA specifies the scalar alpha. Unchanged on exit. .TP 7 X - DOUBLE PRECISION array of dimension at least ( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the n element vector x. Unchanged on exit. .TP 7 INCX - INTEGER. On entry, INCX specifies the increment for the elements of X. INCX must not be zero. Unchanged on exit. .TP 7 AP - DOUBLE PRECISION array of DIMENSION at least ( ( n*( n + 1 ) )/2 ). Before entry with UPLO = \(aqU\(aq or \(aqu\(aq, the array AP must contain the upper triangular part of the symmetric matrix packed sequentially, column by column, so that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 ) respectively, and so on. On exit, the array AP is overwritten by the upper triangular part of the updated matrix. Before entry with UPLO = \(aqL\(aq or \(aql\(aq, the array AP must contain the lower triangular part of the symmetric matrix packed sequentially, column by column, so that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 ) respectively, and so on. On exit, the array AP is overwritten by the lower triangular part of the updated matrix. .SH FURTHER DETAILS Level 2 Blas routine. .br -- Written on 22-October-1986. .br Jack Dongarra, Argonne National Lab. .br Jeremy Du Croz, Nag Central Office. .br Sven Hammarling, Nag Central Office. .br Richard Hanson, Sandia National Labs. .br