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/* slasq5.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 slasq5_(integer *i0, integer *n0, real *z__, integer *pp,
real *tau, real *dmin__, real *dmin1, real *dmin2, real *dn, real *
dnm1, real *dnm2, logical *ieee)
{
/* System generated locals */
integer i__1;
real r__1, r__2;
/* Local variables */
real d__;
integer j4, j4p2;
real emin, temp;
/* -- LAPACK routine (version 3.2) -- */
/* -- Contributed by Osni Marques of the Lawrence Berkeley National -- */
/* -- Laboratory and Beresford Parlett of the Univ. of California at -- */
/* -- Berkeley -- */
/* -- November 2008 -- */
/* -- 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 */
/* ======= */
/* SLASQ5 computes one dqds transform in ping-pong form, one */
/* version for IEEE machines another for non IEEE machines. */
/* Arguments */
/* ========= */
/* I0 (input) INTEGER */
/* First index. */
/* N0 (input) INTEGER */
/* Last index. */
/* Z (input) REAL array, dimension ( 4*N ) */
/* Z holds the qd array. EMIN is stored in Z(4*N0) to avoid */
/* an extra argument. */
/* PP (input) INTEGER */
/* PP=0 for ping, PP=1 for pong. */
/* TAU (input) REAL */
/* This is the shift. */
/* DMIN (output) REAL */
/* Minimum value of d. */
/* DMIN1 (output) REAL */
/* Minimum value of d, excluding D( N0 ). */
/* DMIN2 (output) REAL */
/* Minimum value of d, excluding D( N0 ) and D( N0-1 ). */
/* DN (output) REAL */
/* d(N0), the last value of d. */
/* DNM1 (output) REAL */
/* d(N0-1). */
/* DNM2 (output) REAL */
/* d(N0-2). */
/* IEEE (input) LOGICAL */
/* Flag for IEEE or non IEEE arithmetic. */
/* ===================================================================== */
/* .. Parameter .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Parameter adjustments */
--z__;
/* Function Body */
if (*n0 - *i0 - 1 <= 0) {
return 0;
}
j4 = (*i0 << 2) + *pp - 3;
emin = z__[j4 + 4];
d__ = z__[j4] - *tau;
*dmin__ = d__;
*dmin1 = -z__[j4];
if (*ieee) {
/* Code for IEEE arithmetic. */
if (*pp == 0) {
i__1 = *n0 - 3 << 2;
for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) {
z__[j4 - 2] = d__ + z__[j4 - 1];
temp = z__[j4 + 1] / z__[j4 - 2];
d__ = d__ * temp - *tau;
*dmin__ = dmin(*dmin__,d__);
z__[j4] = z__[j4 - 1] * temp;
/* Computing MIN */
r__1 = z__[j4];
emin = dmin(r__1,emin);
/* L10: */
}
} else {
i__1 = *n0 - 3 << 2;
for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) {
z__[j4 - 3] = d__ + z__[j4];
temp = z__[j4 + 2] / z__[j4 - 3];
d__ = d__ * temp - *tau;
*dmin__ = dmin(*dmin__,d__);
z__[j4 - 1] = z__[j4] * temp;
/* Computing MIN */
r__1 = z__[j4 - 1];
emin = dmin(r__1,emin);
/* L20: */
}
}
/* Unroll last two steps. */
*dnm2 = d__;
*dmin2 = *dmin__;
j4 = (*n0 - 2 << 2) - *pp;
j4p2 = j4 + (*pp << 1) - 1;
z__[j4 - 2] = *dnm2 + z__[j4p2];
z__[j4] = z__[j4p2 + 2] * (z__[j4p2] / z__[j4 - 2]);
*dnm1 = z__[j4p2 + 2] * (*dnm2 / z__[j4 - 2]) - *tau;
*dmin__ = dmin(*dmin__,*dnm1);
*dmin1 = *dmin__;
j4 += 4;
j4p2 = j4 + (*pp << 1) - 1;
z__[j4 - 2] = *dnm1 + z__[j4p2];
z__[j4] = z__[j4p2 + 2] * (z__[j4p2] / z__[j4 - 2]);
*dn = z__[j4p2 + 2] * (*dnm1 / z__[j4 - 2]) - *tau;
*dmin__ = dmin(*dmin__,*dn);
} else {
/* Code for non IEEE arithmetic. */
if (*pp == 0) {
i__1 = *n0 - 3 << 2;
for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) {
z__[j4 - 2] = d__ + z__[j4 - 1];
if (d__ < 0.f) {
return 0;
} else {
z__[j4] = z__[j4 + 1] * (z__[j4 - 1] / z__[j4 - 2]);
d__ = z__[j4 + 1] * (d__ / z__[j4 - 2]) - *tau;
}
*dmin__ = dmin(*dmin__,d__);
/* Computing MIN */
r__1 = emin, r__2 = z__[j4];
emin = dmin(r__1,r__2);
/* L30: */
}
} else {
i__1 = *n0 - 3 << 2;
for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) {
z__[j4 - 3] = d__ + z__[j4];
if (d__ < 0.f) {
return 0;
} else {
z__[j4 - 1] = z__[j4 + 2] * (z__[j4] / z__[j4 - 3]);
d__ = z__[j4 + 2] * (d__ / z__[j4 - 3]) - *tau;
}
*dmin__ = dmin(*dmin__,d__);
/* Computing MIN */
r__1 = emin, r__2 = z__[j4 - 1];
emin = dmin(r__1,r__2);
/* L40: */
}
}
/* Unroll last two steps. */
*dnm2 = d__;
*dmin2 = *dmin__;
j4 = (*n0 - 2 << 2) - *pp;
j4p2 = j4 + (*pp << 1) - 1;
z__[j4 - 2] = *dnm2 + z__[j4p2];
if (*dnm2 < 0.f) {
return 0;
} else {
z__[j4] = z__[j4p2 + 2] * (z__[j4p2] / z__[j4 - 2]);
*dnm1 = z__[j4p2 + 2] * (*dnm2 / z__[j4 - 2]) - *tau;
}
*dmin__ = dmin(*dmin__,*dnm1);
*dmin1 = *dmin__;
j4 += 4;
j4p2 = j4 + (*pp << 1) - 1;
z__[j4 - 2] = *dnm1 + z__[j4p2];
if (*dnm1 < 0.f) {
return 0;
} else {
z__[j4] = z__[j4p2 + 2] * (z__[j4p2] / z__[j4 - 2]);
*dn = z__[j4p2 + 2] * (*dnm1 / z__[j4 - 2]) - *tau;
}
*dmin__ = dmin(*dmin__,*dn);
}
z__[j4 + 2] = *dn;
z__[(*n0 << 2) - *pp] = emin;
return 0;
/* End of SLASQ5 */
} /* slasq5_ */
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