.TH "dlacn2.f" 3 "Wed Oct 15 2014" "Version 3.4.2" "LAPACK" \" -*- nroff -*-
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.SH NAME
dlacn2.f \- 
.SH SYNOPSIS
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.SS "Functions/Subroutines"

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.ti -1c
.RI "subroutine \fBdlacn2\fP (N, V, X, ISGN, EST, KASE, ISAVE)"
.br
.RI "\fI\fBDLACN2\fP estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vector products\&. \fP"
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.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine dlacn2 (integerN, double precision, dimension( * )V, double precision, dimension( * )X, integer, dimension( * )ISGN, double precisionEST, integerKASE, integer, dimension( 3 )ISAVE)"

.PP
\fBDLACN2\fP estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vector products\&.  
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\fBPurpose: \fP
.RS 4

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.nf
 DLACN2 estimates the 1-norm of a square, real matrix A.
 Reverse communication is used for evaluating matrix-vector products.
.fi
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.RE
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\fBParameters:\fP
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\fIN\fP 
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          N is INTEGER
         The order of the matrix.  N >= 1.
.fi
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\fIV\fP 
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          V is DOUBLE PRECISION array, dimension (N)
         On the final return, V = A*W,  where  EST = norm(V)/norm(W)
         (W is not returned).
.fi
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\fIX\fP 
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.nf
          X is DOUBLE PRECISION array, dimension (N)
         On an intermediate return, X should be overwritten by
               A * X,   if KASE=1,
               A**T * X,  if KASE=2,
         and DLACN2 must be re-called with all the other parameters
         unchanged.
.fi
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\fIISGN\fP 
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          ISGN is INTEGER array, dimension (N)
.fi
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\fIEST\fP 
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          EST is DOUBLE PRECISION
         On entry with KASE = 1 or 2 and ISAVE(1) = 3, EST should be
         unchanged from the previous call to DLACN2.
         On exit, EST is an estimate (a lower bound) for norm(A). 
.fi
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\fIKASE\fP 
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          KASE is INTEGER
         On the initial call to DLACN2, KASE should be 0.
         On an intermediate return, KASE will be 1 or 2, indicating
         whether X should be overwritten by A * X  or A**T * X.
         On the final return from DLACN2, KASE will again be 0.
.fi
.PP
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\fIISAVE\fP 
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          ISAVE is INTEGER array, dimension (3)
         ISAVE is used to save variables between calls to DLACN2
.fi
.PP
 
.RE
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\fBAuthor:\fP
.RS 4
Univ\&. of Tennessee 
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Univ\&. of California Berkeley 
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Univ\&. of Colorado Denver 
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NAG Ltd\&. 
.RE
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\fBDate:\fP
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September 2012 
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\fBFurther Details: \fP
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  Originally named SONEST, dated March 16, 1988.

  This is a thread safe version of DLACON, which uses the array ISAVE
  in place of a SAVE statement, as follows:

     DLACON     DLACN2
      JUMP     ISAVE(1)
      J        ISAVE(2)
      ITER     ISAVE(3)
.fi
.PP
 
.RE
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\fBContributors: \fP
.RS 4
Nick Higham, University of Manchester 
.RE
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\fBReferences: \fP
.RS 4
N\&.J\&. Higham, 'FORTRAN codes for estimating the one-norm of
  a real or complex matrix, with applications to condition estimation', ACM Trans\&. Math\&. Soft\&., vol\&. 14, no\&. 4, pp\&. 381-396, December 1988\&. 
.RE
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Definition at line 137 of file dlacn2\&.f\&.
.SH "Author"
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Generated automatically by Doxygen for LAPACK from the source code\&.