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/* laso/dlager.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 "v3p_netlib.h"
/* *********************************************************************** */
/*< SUBROUTINE DLAGER(N, NBAND, NSTART, A, TMIN, TMAX) >*/
/* Subroutine */ int dlager_(integer *n, integer *nband, integer *nstart,
doublereal *a, doublereal *tmin, doublereal *tmax)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2;
doublereal d__1, d__2;
/* Local variables */
integer i__, k, l, m;
doublereal temp;
/* THIS SUBROUTINE COMPUTES BOUNDS ON THE SPECTRUM OF A BY */
/* EXAMINING THE GERSCHGORIN CIRCLES. ONLY THE NEWLY CREATED */
/* CIRCLES ARE EXAMINED */
/* FORMAL PARAMETERS */
/*< INTEGER N, NBAND, NSTART >*/
/*< DOUBLE PRECISION A(NBAND,1), TMIN, TMAX >*/
/* LOCAL VARIABLES */
/*< INTEGER I, K, L, M >*/
/*< DOUBLE PRECISION TEMP >*/
/* FUNCTIONS CALLED */
/*< INTEGER MIN0 >*/
/*< DOUBLE PRECISION DMIN1, DMAX1 >*/
/*< DO 50 K = NSTART, N >*/
/* Parameter adjustments */
a_dim1 = *nband;
a_offset = 1 + a_dim1;
a -= a_offset;
/* Function Body */
i__1 = *n;
for (k = *nstart; k <= i__1; ++k) {
/*< TEMP = 0.0D0 >*/
temp = 0.;
/*< DO 10 I = 2, NBAND >*/
i__2 = *nband;
for (i__ = 2; i__ <= i__2; ++i__) {
/*< TEMP = TEMP + DABS(A(I,K)) >*/
temp += (d__1 = a[i__ + k * a_dim1], abs(d__1));
/*< 10 CONTINUE >*/
/* L10: */
}
/*< 20 L = MIN0(K,NBAND) >*/
/* L20: */
l = min(k,*nband);
/*< IF(L .EQ. 1) GO TO 40 >*/
if (l == 1) {
goto L40;
}
/*< DO 30 I = 2, L >*/
i__2 = l;
for (i__ = 2; i__ <= i__2; ++i__) {
/*< M = K - I + 1 >*/
m = k - i__ + 1;
/*< TEMP = TEMP + DABS(A(I,M)) >*/
temp += (d__1 = a[i__ + m * a_dim1], abs(d__1));
/*< 30 CONTINUE >*/
/* L30: */
}
/*< 40 TMIN = DMIN1(TMIN, A(1,K)-TEMP) >*/
L40:
/* Computing MIN */
d__1 = *tmin, d__2 = a[k * a_dim1 + 1] - temp;
*tmin = min(d__1,d__2);
/*< TMAX = DMAX1(TMAX, A(1,K)+TEMP) >*/
/* Computing MAX */
d__1 = *tmax, d__2 = a[k * a_dim1 + 1] + temp;
*tmax = max(d__1,d__2);
/*< 50 CONTINUE >*/
/* L50: */
}
/*< RETURN >*/
return 0;
/*< END >*/
} /* dlager_ */
#ifdef __cplusplus
}
#endif
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