PDLANTR(l) | LAPACK auxiliary routine (version 1.5) | PDLANTR(l) |
NAME¶
PDLANTR - return the value of the one norm, or the Frobenius norm,SYNOPSIS¶
- DOUBLE PRECISION
- FUNCTION PDLANTR( NORM, UPLO, DIAG, M, N, A,IA, JA, DESCA, WORK )
PURPOSE¶
PDLANTR returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a trapezoidal or triangular distributed matrix sub( A ) denoting A(IA:IA+M-1, JA:JA+N-1).( max(abs(A(i,j))), NORM = 'M' or 'm' with ia <= i <= ia+m-1,
( and ja <= j <= ja+n-1,
(
( norm1( sub( A ) ), NORM = '1', 'O' or 'o'
(
( normI( sub( A ) ), NORM = 'I' or 'i'
(
( normF( sub( A ) ), NORM = 'F', 'f', 'E' or 'e'
DTYPE_A = 1.
the BLACS process grid A is distribu-
ted over. The context itself is glo-
bal, but the handle (the integer
value) may vary.
array A.
array A.
the rows of the array.
the columns of the array.
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.
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( 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
ARGUMENTS¶
- NORM (global input) CHARACTER
- Specifies the value to be returned in PDLANTR as describedabove.
- UPLO (global input) CHARACTER
- Specifies whether the matrix sub( A ) is upper or lowertrapezoidal.= 'U':
Upper trapezoidal
- DIAG (global input) CHARACTER
- Specifies whether or not the distributed matrix sub( A ) hasunit
diagonal.= 'N': Non-unit diagonal
- M (global input) INTEGER
- The number of rows to be operated on i.e the number of rowsof the distributed submatrix sub( A ). When M = 0, PDLANTR is set to zero. M >= 0.
- N (global input) INTEGER
- The number of columns to be operated on i.e the number ofcolumns of the distributed submatrix sub( A ). When N = 0, PDLANTR is set to zero. N >= 0.
- A (local input) DOUBLE PRECISION pointer into the local memory
- to an array of dimension (LLD_A, LOCc(JA+N-1) ) containingthe local pieces of sub( A ).
- IA (global input) INTEGER
- The row index in the global array A indicating the firstrow of sub( A ).
- JA (global input) INTEGER
- The column index in the global array A indicating thefirst column of sub( A ).
- DESCA (global and local input) INTEGER array of dimension DLEN_.
- The array descriptor for the distributed matrix A.
- WORK (local workspace) DOUBLE PRECISION array dimension (LWORK)
- LWORK >= 0 if NORM = 'M' or 'm' (not referenced),Nq0 if NORM = '1', 'O' or 'o', Mp0 if NORM = 'I' or 'i', 0 if NORM = 'F', 'f', 'E' or 'e' (not referenced), where IROFFA = MOD( IA-1, MB_A ), ICOFFA = MOD( JA-1, NB_A ), IAROW = INDXG2P( IA, MB_A, MYROW, RSRC_A, NPROW ), IACOL = INDXG2P( JA, NB_A, MYCOL, CSRC_A, NPCOL ), Mp0 = NUMROC( M+IROFFA, MB_A, MYROW, IAROW, NPROW ), Nq0 = NUMROC( N+ICOFFA, NB_A, MYCOL, IACOL, NPCOL ), INDXG2P and NUMROC are ScaLAPACK tool functions; MYROW, MYCOL, NPROW and NPCOL can be determined by calling the subroutine BLACS_GRIDINFO.
12 May 1997 | LAPACK version 1.5 |