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/* lapack/double/dlacon.f -- translated by f2c (version 20050501).
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
*/
#ifdef __cplusplus
extern "C" {
#endif
#include <stdio.h> /* fprintf */
#include "v3p_netlib.h"
/* Table of constant values */
static integer c__1 = 1;
static doublereal c_b11 = 1.;
/*< SUBROUTINE DLACON( N, V, X, ISGN, EST, KASE ) >*/
/* Subroutine */ int dlacon_(integer *n, doublereal *v, doublereal *x,
integer *isgn, doublereal *est, integer *kase)
{
/* System generated locals */
integer i__1;
doublereal d__1;
/* Builtin functions */
double d_sign(doublereal *, doublereal *);
integer i_dnnt(doublereal *);
/* Local variables */
static integer i__, j, iter;
static doublereal temp;
static integer jump;
extern doublereal dasum_(integer *, doublereal *, integer *);
static integer jlast;
extern /* Subroutine */ int dcopy_(integer *, doublereal *, integer *,
doublereal *, integer *);
extern integer idamax_(integer *, doublereal *, integer *);
static doublereal altsgn, estold;
fprintf(stderr,
"WARNING: dlacon_ has not been converted for thread safety "
"because the vnl test suite does not manage to call it "
"through dgges. Please send the case for which you get this "
"message to the vxl-users mailing list:\n"
"https://lists.sourceforge.net/lists/listinfo/vxl-users\n\n");
/* -- LAPACK auxiliary routine (version 3.0) -- */
/* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., */
/* Courant Institute, Argonne National Lab, and Rice University */
/* February 29, 1992 */
/* .. Scalar Arguments .. */
/*< INTEGER KASE, N >*/
/*< DOUBLE PRECISION EST >*/
/* .. */
/* .. Array Arguments .. */
/*< INTEGER ISGN( * ) >*/
/*< DOUBLE PRECISION V( * ), X( * ) >*/
/* .. */
/* Purpose */
/* ======= */
/* DLACON estimates the 1-norm of a square, real matrix A. */
/* Reverse communication is used for evaluating matrix-vector products. */
/* Arguments */
/* ========= */
/* N (input) INTEGER */
/* The order of the matrix. N >= 1. */
/* V (workspace) DOUBLE PRECISION array, dimension (N) */
/* On the final return, V = A*W, where EST = norm(V)/norm(W) */
/* (W is not returned). */
/* X (input/output) DOUBLE PRECISION array, dimension (N) */
/* On an intermediate return, X should be overwritten by */
/* A * X, if KASE=1, */
/* A' * X, if KASE=2, */
/* and DLACON must be re-called with all the other parameters */
/* unchanged. */
/* ISGN (workspace) INTEGER array, dimension (N) */
/* EST (output) DOUBLE PRECISION */
/* An estimate (a lower bound) for norm(A). */
/* KASE (input/output) INTEGER */
/* On the initial call to DLACON, KASE should be 0. */
/* On an intermediate return, KASE will be 1 or 2, indicating */
/* whether X should be overwritten by A * X or A' * X. */
/* On the final return from DLACON, KASE will again be 0. */
/* Further Details */
/* ======= ======= */
/* Contributed by Nick Higham, University of Manchester. */
/* Originally named SONEST, dated March 16, 1988. */
/* Reference: N.J. Higham, "FORTRAN codes for estimating the one-norm of */
/* a real or complex matrix, with applications to condition estimation", */
/* ACM Trans. Math. Soft., vol. 14, no. 4, pp. 381-396, December 1988. */
/* ===================================================================== */
/* .. Parameters .. */
/*< INTEGER ITMAX >*/
/*< PARAMETER ( ITMAX = 5 ) >*/
/*< DOUBLE PRECISION ZERO, ONE, TWO >*/
/*< PARAMETER ( ZERO = 0.0D+0, ONE = 1.0D+0, TWO = 2.0D+0 ) >*/
/* .. */
/* .. Local Scalars .. */
/*< INTEGER I, ITER, J, JLAST, JUMP >*/
/*< DOUBLE PRECISION ALTSGN, ESTOLD, TEMP >*/
/* .. */
/* .. External Functions .. */
/*< INTEGER IDAMAX >*/
/*< DOUBLE PRECISION DASUM >*/
/*< EXTERNAL IDAMAX, DASUM >*/
/* .. */
/* .. External Subroutines .. */
/*< EXTERNAL DCOPY >*/
/* .. */
/* .. Intrinsic Functions .. */
/*< INTRINSIC ABS, DBLE, NINT, SIGN >*/
/* .. */
/* .. Save statement .. */
/*< SAVE >*/
/* .. */
/* .. Executable Statements .. */
/*< IF( KASE.EQ.0 ) THEN >*/
/* Parameter adjustments */
--isgn;
--x;
--v;
/* Function Body */
if (*kase == 0) {
/*< DO 10 I = 1, N >*/
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
/*< X( I ) = ONE / DBLE( N ) >*/
x[i__] = 1. / (doublereal) (*n);
/*< 10 CONTINUE >*/
/* L10: */
}
/*< KASE = 1 >*/
*kase = 1;
/*< JUMP = 1 >*/
jump = 1;
/*< RETURN >*/
return 0;
/*< END IF >*/
}
/*< GO TO ( 20, 40, 70, 110, 140 )JUMP >*/
switch (jump) {
case 1: goto L20;
case 2: goto L40;
case 3: goto L70;
case 4: goto L110;
case 5: goto L140;
}
/* ................ ENTRY (JUMP = 1) */
/* FIRST ITERATION. X HAS BEEN OVERWRITTEN BY A*X. */
/*< 20 CONTINUE >*/
L20:
/*< IF( N.EQ.1 ) THEN >*/
if (*n == 1) {
/*< V( 1 ) = X( 1 ) >*/
v[1] = x[1];
/*< EST = ABS( V( 1 ) ) >*/
*est = abs(v[1]);
/* ... QUIT */
/*< GO TO 150 >*/
goto L150;
/*< END IF >*/
}
/*< EST = DASUM( N, X, 1 ) >*/
*est = dasum_(n, &x[1], &c__1);
/*< DO 30 I = 1, N >*/
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
/*< X( I ) = SIGN( ONE, X( I ) ) >*/
x[i__] = d_sign(&c_b11, &x[i__]);
/*< ISGN( I ) = NINT( X( I ) ) >*/
isgn[i__] = i_dnnt(&x[i__]);
/*< 30 CONTINUE >*/
/* L30: */
}
/*< KASE = 2 >*/
*kase = 2;
/*< JUMP = 2 >*/
jump = 2;
/*< RETURN >*/
return 0;
/* ................ ENTRY (JUMP = 2) */
/* FIRST ITERATION. X HAS BEEN OVERWRITTEN BY TRANSPOSE(A)*X. */
/*< 40 CONTINUE >*/
L40:
/*< J = IDAMAX( N, X, 1 ) >*/
j = idamax_(n, &x[1], &c__1);
/*< ITER = 2 >*/
iter = 2;
/* MAIN LOOP - ITERATIONS 2,3,...,ITMAX. */
/*< 50 CONTINUE >*/
L50:
/*< DO 60 I = 1, N >*/
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
/*< X( I ) = ZERO >*/
x[i__] = 0.;
/*< 60 CONTINUE >*/
/* L60: */
}
/*< X( J ) = ONE >*/
x[j] = 1.;
/*< KASE = 1 >*/
*kase = 1;
/*< JUMP = 3 >*/
jump = 3;
/*< RETURN >*/
return 0;
/* ................ ENTRY (JUMP = 3) */
/* X HAS BEEN OVERWRITTEN BY A*X. */
/*< 70 CONTINUE >*/
L70:
/*< CALL DCOPY( N, X, 1, V, 1 ) >*/
dcopy_(n, &x[1], &c__1, &v[1], &c__1);
/*< ESTOLD = EST >*/
estold = *est;
/*< EST = DASUM( N, V, 1 ) >*/
*est = dasum_(n, &v[1], &c__1);
/*< DO 80 I = 1, N >*/
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
/*< >*/
d__1 = d_sign(&c_b11, &x[i__]);
if (i_dnnt(&d__1) != isgn[i__]) {
goto L90;
}
/*< 80 CONTINUE >*/
/* L80: */
}
/* REPEATED SIGN VECTOR DETECTED, HENCE ALGORITHM HAS CONVERGED. */
/*< GO TO 120 >*/
goto L120;
/*< 90 CONTINUE >*/
L90:
/* TEST FOR CYCLING. */
/*< >*/
if (*est <= estold) {
goto L120;
}
/*< DO 100 I = 1, N >*/
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
/*< X( I ) = SIGN( ONE, X( I ) ) >*/
x[i__] = d_sign(&c_b11, &x[i__]);
/*< ISGN( I ) = NINT( X( I ) ) >*/
isgn[i__] = i_dnnt(&x[i__]);
/*< 100 CONTINUE >*/
/* L100: */
}
/*< KASE = 2 >*/
*kase = 2;
/*< JUMP = 4 >*/
jump = 4;
/*< RETURN >*/
return 0;
/* ................ ENTRY (JUMP = 4) */
/* X HAS BEEN OVERWRITTEN BY TRANSPOSE(A)*X. */
/*< 110 CONTINUE >*/
L110:
/*< JLAST = J >*/
jlast = j;
/*< J = IDAMAX( N, X, 1 ) >*/
j = idamax_(n, &x[1], &c__1);
/*< IF( ( X( JLAST ).NE.ABS( X( J ) ) ) .AND. ( ITER.LT.ITMAX ) ) THEN >*/
if (x[jlast] != (d__1 = x[j], abs(d__1)) && iter < 5) {
/*< ITER = ITER + 1 >*/
++iter;
/*< GO TO 50 >*/
goto L50;
/*< END IF >*/
}
/* ITERATION COMPLETE. FINAL STAGE. */
/*< 120 CONTINUE >*/
L120:
/*< ALTSGN = ONE >*/
altsgn = 1.;
/*< DO 130 I = 1, N >*/
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
/*< X( I ) = ALTSGN*( ONE+DBLE( I-1 ) / DBLE( N-1 ) ) >*/
x[i__] = altsgn * ((doublereal) (i__ - 1) / (doublereal) (*n - 1) +
1.);
/*< ALTSGN = -ALTSGN >*/
altsgn = -altsgn;
/*< 130 CONTINUE >*/
/* L130: */
}
/*< KASE = 1 >*/
*kase = 1;
/*< JUMP = 5 >*/
jump = 5;
/*< RETURN >*/
return 0;
/* ................ ENTRY (JUMP = 5) */
/* X HAS BEEN OVERWRITTEN BY A*X. */
/*< 140 CONTINUE >*/
L140:
/*< TEMP = TWO*( DASUM( N, X, 1 ) / DBLE( 3*N ) ) >*/
temp = dasum_(n, &x[1], &c__1) / (doublereal) (*n * 3) * 2.;
/*< IF( TEMP.GT.EST ) THEN >*/
if (temp > *est) {
/*< CALL DCOPY( N, X, 1, V, 1 ) >*/
dcopy_(n, &x[1], &c__1, &v[1], &c__1);
/*< EST = TEMP >*/
*est = temp;
/*< END IF >*/
}
/*< 150 CONTINUE >*/
L150:
/*< KASE = 0 >*/
*kase = 0;
/*< RETURN >*/
return 0;
/* End of DLACON */
/*< END >*/
} /* dlacon_ */
#ifdef __cplusplus
}
#endif
|
