dlaswp.c

/* dlaswp.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 "clapack.h"


/* Subroutine */ int dlaswp_(integer *n, doublereal *a, integer *lda, integer 
	*k1, integer *k2, integer *ipiv, integer *incx)
{
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2, i__3, i__4;

    /* Local variables */
    integer i__, j, k, i1, i2, n32, ip, ix, ix0, inc;
    doublereal temp;


/*  -- LAPACK auxiliary routine (version 3.2) -- */
/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/*     November 2006 */

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

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

/*  DLASWP performs a series of row interchanges on the matrix A. */
/*  One row interchange is initiated for each of rows K1 through K2 of A. */

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

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

/*  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N) */
/*          On entry, the matrix of column dimension N to which the row */
/*          interchanges will be applied. */
/*          On exit, the permuted matrix. */

/*  LDA     (input) INTEGER */
/*          The leading dimension of the array A. */

/*  K1      (input) INTEGER */
/*          The first element of IPIV for which a row interchange will */
/*          be done. */

/*  K2      (input) INTEGER */
/*          The last element of IPIV for which a row interchange will */
/*          be done. */

/*  IPIV    (input) INTEGER array, dimension (K2*abs(INCX)) */
/*          The vector of pivot indices.  Only the elements in positions */
/*          K1 through K2 of IPIV are accessed. */
/*          IPIV(K) = L implies rows K and L are to be interchanged. */

/*  INCX    (input) INTEGER */
/*          The increment between successive values of IPIV.  If IPIV */
/*          is negative, the pivots are applied in reverse order. */

/*  Further Details */
/*  =============== */

/*  Modified by */
/*   R. C. Whaley, Computer Science Dept., Univ. of Tenn., Knoxville, USA */

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

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

/*     Interchange row I with row IPIV(I) for each of rows K1 through K2. */

    /* Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --ipiv;

    /* Function Body */
    if (*incx > 0) {
	ix0 = *k1;
	i1 = *k1;
	i2 = *k2;
	inc = 1;
    } else if (*incx < 0) {
	ix0 = (1 - *k2) * *incx + 1;
	i1 = *k2;
	i2 = *k1;
	inc = -1;
    } else {
	return 0;
    }

    n32 = *n / 32 << 5;
    if (n32 != 0) {
	i__1 = n32;
	for (j = 1; j <= i__1; j += 32) {
	    ix = ix0;
	    i__2 = i2;
	    i__3 = inc;
	    for (i__ = i1; i__3 < 0 ? i__ >= i__2 : i__ <= i__2; i__ += i__3) 
		    {
		ip = ipiv[ix];
		if (ip != i__) {
		    i__4 = j + 31;
		    for (k = j; k <= i__4; ++k) {
			temp = a[i__ + k * a_dim1];
			a[i__ + k * a_dim1] = a[ip + k * a_dim1];
			a[ip + k * a_dim1] = temp;
/* L10: */
		    }
		}
		ix += *incx;
/* L20: */
	    }
/* L30: */
	}
    }
    if (n32 != *n) {
	++n32;
	ix = ix0;
	i__1 = i2;
	i__3 = inc;
	for (i__ = i1; i__3 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__3) {
	    ip = ipiv[ix];
	    if (ip != i__) {
		i__2 = *n;
		for (k = n32; k <= i__2; ++k) {
		    temp = a[i__ + k * a_dim1];
		    a[i__ + k * a_dim1] = a[ip + k * a_dim1];
		    a[ip + k * a_dim1] = temp;
/* L40: */
		}
	    }
	    ix += *incx;
/* L50: */
	}
    }

    return 0;

/*     End of DLASWP */

} /* dlaswp_ */