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HPL_pdlange(3)               HPL Library Functions              HPL_pdlange(3)


NAME

       HPL_pdlange - Compute ||A||.


SYNOPSIS

       #include "hpl.h"

       double HPL_pdlange( const HPL_T_grid * GRID, const HPL_T_NORM NORM,
       const int M, const int N, const int NB, const double * A, const int LDA
       );


DESCRIPTION

       HPL_pdlange returns  the value of the one norm,  or the infinity norm,
       or the element of largest absolute value of a distributed matrix A:

          max(abs(A(i,j))) when NORM = HPL_NORM_A,
          norm1(A),        when NORM = HPL_NORM_1,
          normI(A),        when NORM = HPL_NORM_I,

       where norm1 denotes the one norm of a matrix (maximum column sum) and
       normI denotes  the infinity norm of a matrix (maximum row sum).  Note
       that max(abs(A(i,j))) is not a matrix norm.


ARGUMENTS

       GRID    (local input)           const HPL_T_grid *
               On entry,  GRID  points  to the data structure containing the
               process grid information.

       NORM    (global input)          const HPL_T_NORM
               On entry,  NORM  specifies  the  value to be returned by this
               function as described above.

       M       (global input)          const int
               On entry,  M  specifies  the number  of rows of the matrix A.
               M must be at least zero.

       N       (global input)          const int
               On entry,  N specifies the number of columns of the matrix A.
               N must be at least zero.

       NB      (global input)          const int
               On entry,  NB specifies the blocking factor used to partition
               and distribute the matrix. NB must be larger than one.

       A       (local input)           const double *
               On entry,  A  points to an array of dimension  (LDA,LocQ(N)),
               that contains the local pieces of the distributed matrix A.

       LDA     (local input)           const int
               On entry, LDA specifies the leading dimension of the array A.
               LDA must be at least max(1,LocP(M)).


SEE ALSO

       HPL_pdlaprnt (3), HPL_fprintf (3).

HPL 2.1                        October 26, 2012                 HPL_pdlange(3)

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