starpu-max/min-dgels/base/SRC/drscl.c

/* drscl.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 _starpu_drscl_(integer *n, doublereal *sa, doublereal *sx, 
	integer *incx)
{
    doublereal mul, cden;
    logical done;
    doublereal cnum, cden1, cnum1;
    extern /* Subroutine */ int _starpu_dscal_(integer *, doublereal *, doublereal *, 
	    integer *), _starpu_dlabad_(doublereal *, doublereal *);
    extern doublereal _starpu_dlamch_(char *);
    doublereal bignum, smlnum;


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

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

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

/*  DRSCL multiplies an n-element real vector x by the real scalar 1/a. */
/*  This is done without overflow or underflow as long as */
/*  the final result x/a does not overflow or underflow. */

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

/*  N       (input) INTEGER */
/*          The number of components of the vector x. */

/*  SA      (input) DOUBLE PRECISION */
/*          The scalar a which is used to divide each component of x. */
/*          SA must be >= 0, or the subroutine will divide by zero. */

/*  SX      (input/output) DOUBLE PRECISION array, dimension */
/*                         (1+(N-1)*abs(INCX)) */
/*          The n-element vector x. */

/*  INCX    (input) INTEGER */
/*          The increment between successive values of the vector SX. */
/*          > 0:  SX(1) = X(1) and SX(1+(i-1)*INCX) = x(i),     1< i<= n */

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

/*     .. Parameters .. */
/*     .. */
/*     .. Local Scalars .. */
/*     .. */
/*     .. External Functions .. */
/*     .. */
/*     .. External Subroutines .. */
/*     .. */
/*     .. Intrinsic Functions .. */
/*     .. */
/*     .. Executable Statements .. */

/*     Quick return if possible */

    /* Parameter adjustments */
    --sx;

    /* Function Body */
    if (*n <= 0) {
	return 0;
    }

/*     Get machine parameters */

    smlnum = _starpu_dlamch_("S");
    bignum = 1. / smlnum;
    _starpu_dlabad_(&smlnum, &bignum);

/*     Initialize the denominator to SA and the numerator to 1. */

    cden = *sa;
    cnum = 1.;

L10:
    cden1 = cden * smlnum;
    cnum1 = cnum / bignum;
    if (abs(cden1) > abs(cnum) && cnum != 0.) {

/*        Pre-multiply X by SMLNUM if CDEN is large compared to CNUM. */

	mul = smlnum;
	done = FALSE_;
	cden = cden1;
    } else if (abs(cnum1) > abs(cden)) {

/*        Pre-multiply X by BIGNUM if CDEN is small compared to CNUM. */

	mul = bignum;
	done = FALSE_;
	cnum = cnum1;
    } else {

/*        Multiply X by CNUM / CDEN and return. */

	mul = cnum / cden;
	done = TRUE_;
    }

/*     Scale the vector X by MUL */

    _starpu_dscal_(n, &mul, &sx[1], incx);

    if (! done) {
	goto L10;
    }

    return 0;

/*     End of DRSCL */

} /* _starpu_drscl_ */