p?latra

Computes the trace of a general square distributed matrix.

Syntax

val = pslatra(n, a, ia, ja, desca)

val = pdlatra(n, a, ia, ja, desca)

val = pclatra(n, a, ia, ja, desca)

val = pzlatra(n, a, ia, ja, desca)

Include Files

C: mkl_scalapack.h

Description

This function computes the trace of an n-by-n distributed matrix sub(A) denoting A(ia:ia+n-1, ja:ja+n-1). The result is left on every process of the grid.

Input Parameters

n

(global) INTEGER.

The number of rows and columns to be operated on, that is, the order of the distributed submatrix sub(A). n ≥0.

a

(local).

Real for pslatra

DOUBLE PRECISION for pdlatra

COMPLEX for pclatra

COMPLEX*16 for pzlatra.

Pointer into the local memory to an array of DIMENSION(lld_a, LOCc(ja+n-1)) containing the local pieces of the distributed matrix, the trace of which is to be computed.

ia, ja

(global) INTEGER. The row and column indices respectively in the global array A indicating the first row and the first column of the submatrix sub(A), respectively.

desca

(global and local) INTEGER array of DIMENSION (dlen_). The array descriptor for the distributed matrix A.

Output Parameters

val: The value returned by the fuction.