---
name: "pzlacgv"
section: "3"
platform: "linux"
package: "scalapack-doc"
version: "1.5-11"
release: "Debian 11 (Bullseye)"
platforms: ["linux"]
url: "https://new.carta.tech/pzlacgv"
---

# pzlacgv(3)

conjugate a complex vector of length N, sub( X ), where sub( X ) denotes X(IX,JX:JX+N-1) if INCX = DESCX( M\_ ) and X(IX:IX+N-1,JX) if INCX = 1, and Notes ===== Each global data object is described by an associated description vector

## NAME

PZLACGV - conjugate a complex vector of length N, sub( X ), where sub( X ) denotes X(IX,JX:JX+N-1) if INCX = DESCX( M\_ ) and X(IX:IX+N-1,JX) if INCX = 1, and  Notes =====  Each global data object is described by an associated description vector

## SYNOPSIS

- SUBROUTINE PZLACGV(

  N, X, IX, JX, DESCX, INCX )

- INTEGER

  INCX, IX, JX, N

- INTEGER

  DESCX( \* )

- COMPLEX\*16

  X( \* )

## PURPOSE

PZLACGV conjugates a complex vector of length N, sub( X ), where sub( X ) denotes X(IX,JX:JX+N-1) if INCX = DESCX( M\_ ) and X(IX:IX+N-1,JX) if INCX = 1, and the mapping between an object element and its corresponding process and memory location.\

Let A be a generic term for any 2D block cyclicly distributed array. Such a global array has an associated description vector DESCA. In the following comments, the character \_ should be read as "of the global array".\

NOTATION        STORED IN      EXPLANATION\
 \--------------- -------------- -------------------------------------- DTYPE\_A(global) DESCA( DTYPE\_ )The descriptor type.  In this case,\
                                DTYPE\_A = 1.\
 CTXT\_A (global) DESCA( CTXT\_ ) The BLACS context handle, indicating\
                                the BLACS process grid A is distribu-\
                                ted over. The context itself is glo-\
                                bal, but the handle (the integer\
                                value) may vary.\
 M\_A    (global) DESCA( M\_ )    The number of rows in the global\
                                array A.\
 N\_A    (global) DESCA( N\_ )    The number of columns in the global\
                                array A.\
 MB\_A   (global) DESCA( MB\_ )   The blocking factor used to distribute\
                                the rows of the array.\
 NB\_A   (global) DESCA( NB\_ )   The blocking factor used to distribute\
                                the columns of the array.\
 RSRC\_A (global) DESCA( RSRC\_ ) The process row over which the first\
                                row of the array A is distributed. CSRC\_A (global) DESCA( CSRC\_ ) The process column over which the\
                                first column of the array A is\
                                distributed.\
 LLD\_A  (local)  DESCA( LLD\_ )  The leading dimension of the local\
                                array.  LLD\_A \>= MAX(1,LOCr(M\_A)).

Let K be the number of rows or columns of a distributed matrix, and assume that its process grid has dimension p x q.\
 LOCr( K ) denotes the number of elements of K that a process would receive if K were distributed over the p processes of its process column.\
 Similarly, LOCc( K ) denotes the number of elements of K that a process would receive if K were distributed over the q processes of its process row.\
 The values of LOCr() and LOCc() may be determined via a call to the ScaLAPACK tool function, NUMROC:\
\
         LOCr( M ) = NUMROC( M, MB\_A, MYROW, RSRC\_A, NPROW ),\
         LOCc( N ) = NUMROC( N, NB\_A, MYCOL, CSRC\_A, NPCOL ). An upper bound for these quantities may be computed by:\
\
         LOCr( M ) \<= ceil( ceil(M/MB\_A)/NPROW )\*MB\_A\
\
         LOCc( N ) \<= ceil( ceil(N/NB\_A)/NPCOL )\*NB\_A\

Because vectors may be viewed as a subclass of matrices, a distributed vector is considered to be a distributed matrix.

## ARGUMENTS

- N (global input) INTEGER

  The length of the distributed vector sub( X ).

- X (local input/local output) COMPLEX\*16 pointer into the

  local memory to an array of dimension (LLD\_X,\*). On entry the vector to be conjugated x( i )  = X(IX+(JX-1)\*M\_X +(i-1)\*INCX ), 1 \<= i \<= N. On exit the conjugated vector.

- IX (global input) INTEGER

  The row index in the global array X indicating the first row of sub( X ).

- JX (global input) INTEGER

  The column index in the global array X indicating the first column of sub( X ).

- DESCX (global and local input) INTEGER array of dimension DLEN\_.

  The array descriptor for the distributed matrix X.

- INCX (global input) INTEGER

  The global increment for the elements of X. Only two values of INCX are supported in this version, namely 1 and M\_X. INCX must not be zero.