slaswp.c

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/* slaswp.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 "f2c.h"
#include "blaswrap.h"

/* Subroutine */ int slaswp_(integer *n, real *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;
    real temp;


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

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

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

/*  SLASWP 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) REAL 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 SLASWP */

} /* slaswp_ */