lapack/ilaslr.c

/* ilaslr.f -- translated by f2c (version 20061008).
   You must link the resulting object file with libf2c:
	on Microsoft Windows system, link with libf2c.lib;
	on Linux or Unix systems, link with .../path/to/libf2c.a -lm
	or, if you install libf2c.a in a standard place, with -lf2c -lm
	-- in that order, at the end of the command line, as in
		cc *.o -lf2c -lm
	Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,

		http://www.netlib.org/f2c/libf2c.zip
*/

#include "blaswrap.h"
#include "lapack_datatypes.h"

integer ilaslr_(integer *m, integer *n, real *a, integer *lda)
{
    /* System generated locals */
    integer a_dim1, a_offset, ret_val, i__1;

    /* Local variables */
    integer i__, j;


/*  -- LAPACK auxiliary routine (version 3.2.1)                        -- */

/*  -- April 2009                                                      -- */

/*  -- LAPACK is a software package provided by Univ. of Tennessee,    -- */
/*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */

/*     .. Scalar Arguments .. */
/*     .. */
/*     .. Array Arguments .. */
/*     .. */

/*  Purpose */
/*  ======= */

/*  ILASLR scans A for its last non-zero row. */

/*  Arguments */
/*  ========= */

/*  M       (input) INTEGER */
/*          The number of rows of the matrix A. */

/*  N       (input) INTEGER */
/*          The number of columns of the matrix A. */

/*  A       (input) REAL             array, dimension (LDA,N) */
/*          The m by n matrix A. */

/*  LDA     (input) INTEGER */
/*          The leading dimension of the array A. LDA >= max(1,M). */

/*  ===================================================================== */

/*     .. Parameters .. */
/*     .. */
/*     .. Local Scalars .. */
/*     .. */
/*     .. Executable Statements .. */

/*     Quick test for the common case where one corner is non-zero. */
    /* Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;

    /* Function Body */
    if (*m == 0) {
	ret_val = *m;
    } else if (a[*m + a_dim1] != 0.f || a[*m + *n * a_dim1] != 0.f) {
	ret_val = *m;
    } else {
/*     Scan up each column tracking the last zero row seen. */
	ret_val = 0;
	i__1 = *n;
	for (j = 1; j <= i__1; ++j) {
	    for (i__ = *m; i__ >= 1; --i__) {
		if (a[i__ + j * a_dim1] != 0.f) {
		    break;
		}
	    }
	    ret_val = max(ret_val,i__);
	}
    }
    return ret_val;
} /* ilaslr_ */