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/* lapack/double/dlanhs.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"
/* Table of constant values */
static integer c__1 = 1;
/*< DOUBLE PRECISION FUNCTION DLANHS( NORM, N, A, LDA, WORK ) >*/
doublereal dlanhs_(char *norm, integer *n, doublereal *a, integer *lda,
doublereal *work, ftnlen norm_len)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3, i__4;
doublereal ret_val, d__1, d__2, d__3;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer i__, j;
doublereal sum, scale;
extern logical lsame_(char *, char *, ftnlen, ftnlen);
doublereal value=0;
extern /* Subroutine */ int dlassq_(integer *, doublereal *, integer *,
doublereal *, doublereal *);
(void)norm_len;
/* -- LAPACK auxiliary routine (version 3.0) -- */
/* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., */
/* Courant Institute, Argonne National Lab, and Rice University */
/* October 31, 1992 */
/* .. Scalar Arguments .. */
/*< CHARACTER NORM >*/
/*< INTEGER LDA, N >*/
/* .. */
/* .. Array Arguments .. */
/*< DOUBLE PRECISION A( LDA, * ), WORK( * ) >*/
/* .. */
/* Purpose */
/* ======= */
/* DLANHS returns the value of the one norm, or the Frobenius norm, or */
/* the infinity norm, or the element of largest absolute value of a */
/* Hessenberg matrix A. */
/* Description */
/* =========== */
/* DLANHS returns the value */
/* DLANHS = ( max(abs(A(i,j))), NORM = 'M' or 'm' */
/* ( */
/* ( norm1(A), NORM = '1', 'O' or 'o' */
/* ( */
/* ( normI(A), NORM = 'I' or 'i' */
/* ( */
/* ( normF(A), NORM = 'F', 'f', 'E' or 'e' */
/* where norm1 denotes the one norm of a matrix (maximum column sum), */
/* normI denotes the infinity norm of a matrix (maximum row sum) and */
/* normF denotes the Frobenius norm of a matrix (square root of sum of */
/* squares). Note that max(abs(A(i,j))) is not a matrix norm. */
/* Arguments */
/* ========= */
/* NORM (input) CHARACTER*1 */
/* Specifies the value to be returned in DLANHS as described */
/* above. */
/* N (input) INTEGER */
/* The order of the matrix A. N >= 0. When N = 0, DLANHS is */
/* set to zero. */
/* A (input) DOUBLE PRECISION array, dimension (LDA,N) */
/* The n by n upper Hessenberg matrix A; the part of A below the */
/* first sub-diagonal is not referenced. */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. LDA >= max(N,1). */
/* WORK (workspace) DOUBLE PRECISION array, dimension (LWORK), */
/* where LWORK >= N when NORM = 'I'; otherwise, WORK is not */
/* referenced. */
/* ===================================================================== */
/* .. Parameters .. */
/*< DOUBLE PRECISION ONE, ZERO >*/
/*< PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 ) >*/
/* .. */
/* .. Local Scalars .. */
/*< INTEGER I, J >*/
/*< DOUBLE PRECISION SCALE, SUM, VALUE >*/
/* .. */
/* .. External Subroutines .. */
/*< EXTERNAL DLASSQ >*/
/* .. */
/* .. External Functions .. */
/*< LOGICAL LSAME >*/
/*< EXTERNAL LSAME >*/
/* .. */
/* .. Intrinsic Functions .. */
/*< INTRINSIC ABS, MAX, MIN, SQRT >*/
/* .. */
/* .. Executable Statements .. */
/*< IF( N.EQ.0 ) THEN >*/
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--work;
/* Function Body */
if (*n == 0) {
/*< VALUE = ZERO >*/
value = 0.;
/*< ELSE IF( LSAME( NORM, 'M' ) ) THEN >*/
} else if (lsame_(norm, "M", (ftnlen)1, (ftnlen)1)) {
/* Find max(abs(A(i,j))). */
/*< VALUE = ZERO >*/
value = 0.;
/*< DO 20 J = 1, N >*/
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/*< DO 10 I = 1, MIN( N, J+1 ) >*/
/* Computing MIN */
i__3 = *n, i__4 = j + 1;
i__2 = min(i__3,i__4);
for (i__ = 1; i__ <= i__2; ++i__) {
/*< VALUE = MAX( VALUE, ABS( A( I, J ) ) ) >*/
/* Computing MAX */
d__2 = value, d__3 = (d__1 = a[i__ + j * a_dim1], abs(d__1));
value = max(d__2,d__3);
/*< 10 CONTINUE >*/
/* L10: */
}
/*< 20 CONTINUE >*/
/* L20: */
}
/*< ELSE IF( ( LSAME( NORM, 'O' ) ) .OR. ( NORM.EQ.'1' ) ) THEN >*/
} else if (lsame_(norm, "O", (ftnlen)1, (ftnlen)1) || *(unsigned char *)
norm == '1') {
/* Find norm1(A). */
/*< VALUE = ZERO >*/
value = 0.;
/*< DO 40 J = 1, N >*/
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/*< SUM = ZERO >*/
sum = 0.;
/*< DO 30 I = 1, MIN( N, J+1 ) >*/
/* Computing MIN */
i__3 = *n, i__4 = j + 1;
i__2 = min(i__3,i__4);
for (i__ = 1; i__ <= i__2; ++i__) {
/*< SUM = SUM + ABS( A( I, J ) ) >*/
sum += (d__1 = a[i__ + j * a_dim1], abs(d__1));
/*< 30 CONTINUE >*/
/* L30: */
}
/*< VALUE = MAX( VALUE, SUM ) >*/
value = max(value,sum);
/*< 40 CONTINUE >*/
/* L40: */
}
/*< ELSE IF( LSAME( NORM, 'I' ) ) THEN >*/
} else if (lsame_(norm, "I", (ftnlen)1, (ftnlen)1)) {
/* Find normI(A). */
/*< DO 50 I = 1, N >*/
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
/*< WORK( I ) = ZERO >*/
work[i__] = 0.;
/*< 50 CONTINUE >*/
/* L50: */
}
/*< DO 70 J = 1, N >*/
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/*< DO 60 I = 1, MIN( N, J+1 ) >*/
/* Computing MIN */
i__3 = *n, i__4 = j + 1;
i__2 = min(i__3,i__4);
for (i__ = 1; i__ <= i__2; ++i__) {
/*< WORK( I ) = WORK( I ) + ABS( A( I, J ) ) >*/
work[i__] += (d__1 = a[i__ + j * a_dim1], abs(d__1));
/*< 60 CONTINUE >*/
/* L60: */
}
/*< 70 CONTINUE >*/
/* L70: */
}
/*< VALUE = ZERO >*/
value = 0.;
/*< DO 80 I = 1, N >*/
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
/*< VALUE = MAX( VALUE, WORK( I ) ) >*/
/* Computing MAX */
d__1 = value, d__2 = work[i__];
value = max(d__1,d__2);
/*< 80 CONTINUE >*/
/* L80: */
}
/*< ELSE IF( ( LSAME( NORM, 'F' ) ) .OR. ( LSAME( NORM, 'E' ) ) ) THEN >*/
} else if (lsame_(norm, "F", (ftnlen)1, (ftnlen)1) || lsame_(norm, "E", (
ftnlen)1, (ftnlen)1)) {
/* Find normF(A). */
/*< SCALE = ZERO >*/
scale = 0.;
/*< SUM = ONE >*/
sum = 1.;
/*< DO 90 J = 1, N >*/
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/*< CALL DLASSQ( MIN( N, J+1 ), A( 1, J ), 1, SCALE, SUM ) >*/
/* Computing MIN */
i__3 = *n, i__4 = j + 1;
i__2 = min(i__3,i__4);
dlassq_(&i__2, &a[j * a_dim1 + 1], &c__1, &scale, &sum);
/*< 90 CONTINUE >*/
/* L90: */
}
/*< VALUE = SCALE*SQRT( SUM ) >*/
value = scale * sqrt(sum);
/*< END IF >*/
}
/*< DLANHS = VALUE >*/
ret_val = value;
/*< RETURN >*/
return ret_val;
/* End of DLANHS */
/*< END >*/
} /* dlanhs_ */
#ifdef __cplusplus
}
#endif
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