# HPL_rollN man page

HPL_rollN — Roll U and forward the column panel.

## Synopsis

**#include "hpl.h"****void HPL_rollN( HPL_T_panel *** *PBCST*, **int *** *IFLAG*, **HPL_T_panel *** *PANEL*, **const int** *N*, **double *** *U*, **const int** *LDU*, **const int *** *IPLEN*, **const int *** *IPMAP*, **const int *** *IPMAPM1* **);**

## Description

**HPL_rollN** rolls the local arrays containing the local pieces of U, so that on exit to this function U is replicated in every process row. In addition, this function probe for the presence of the column panel and forwards it when available.

## Arguments

- PBCST (local input/output) HPL_T_panel *
- On entry, PBCST points to the data structure containing the panel (to be broadcast) information.
- IFLAG (local input/output) int *
- On entry, IFLAG indicates whether or not the broadcast has already been completed. If not, probing will occur, and the outcome will be contained in IFLAG on exit.
- PANEL (local input/output) HPL_T_panel *
- On entry, PANEL points to the data structure containing the panel (to be rolled) information.
- N (local input) const int
- On entry, N specifies the number of columns of U. N must be at least zero.
- U (local input/output) double *
- On entry, U is an array of dimension (LDU,*) containing the local pieces of U in each process row.
- LDU (local input) const int
- On entry, LDU specifies the local leading dimension of U. LDU should be at least MAX(1,IPLEN[NPROW]).
- IPLEN (global input) const int *
- On entry, IPLEN is an array of dimension NPROW+1. This array is such that IPLEN[i+1] - IPLEN[i] is the number of rows of U in each process row.
- IPMAP (global input) const int *
- On entry, IMAP is an array of dimension NPROW. This array contains the logarithmic mapping of the processes. In other words, IMAP[myrow] is the absolute coordinate of the sorted process.
- IPMAPM1 (global input) const int *
- On entry, IMAPM1 is an array of dimension NPROW. This array contains the inverse of the logarithmic mapping contained in IMAP: For i in [0.. NPROW) IMAPM1[IMAP[i]] = i.

## See Also

**HPL_pdlaswp01N** (3).

## Info

October 26, 2012 HPL 2.1 HPL Library Functions