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/* lapack/double/dlanst.f -- translated by f2c (version 20090411).
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 DLANST( NORM, N, D, E ) >*/
doublereal dlanst_(char *norm, integer *n, doublereal *d__, doublereal *e,
ftnlen norm_len)
{
/* System generated locals */
integer i__1;
doublereal ret_val, d__1, d__2, d__3, d__4, d__5;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer i__;
doublereal sum, scale;
extern logical lsame_(const char *, const char *, ftnlen, ftnlen);
doublereal anorm;
extern /* Subroutine */ int dlassq_(integer *, doublereal *, integer *,
doublereal *, doublereal *);
/* -- LAPACK auxiliary routine (version 3.2) -- */
/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/* November 2006 */
/* .. Scalar Arguments .. */
/*< CHARACTER NORM >*/
/*< INTEGER N >*/
/* .. */
/* .. Array Arguments .. */
/*< DOUBLE PRECISION D( * ), E( * ) >*/
/* .. */
/* Purpose */
/* ======= */
/* DLANST returns the value of the one norm, or the Frobenius norm, or */
/* the infinity norm, or the element of largest absolute value of a */
/* real symmetric tridiagonal matrix A. */
/* Description */
/* =========== */
/* DLANST returns the value */
/* DLANST = ( 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 consistent matrix norm. */
/* Arguments */
/* ========= */
/* NORM (input) CHARACTER*1 */
/* Specifies the value to be returned in DLANST as described */
/* above. */
/* N (input) INTEGER */
/* The order of the matrix A. N >= 0. When N = 0, DLANST is */
/* set to zero. */
/* D (input) DOUBLE PRECISION array, dimension (N) */
/* The diagonal elements of A. */
/* E (input) DOUBLE PRECISION array, dimension (N-1) */
/* The (n-1) sub-diagonal or super-diagonal elements of A. */
/* ===================================================================== */
/* .. Parameters .. */
/*< DOUBLE PRECISION ONE, ZERO >*/
/*< PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 ) >*/
/* .. */
/* .. Local Scalars .. */
/*< INTEGER I >*/
/*< DOUBLE PRECISION ANORM, SCALE, SUM >*/
/* .. */
/* .. External Functions .. */
/*< LOGICAL LSAME >*/
/*< EXTERNAL LSAME >*/
/* .. */
/* .. External Subroutines .. */
/*< EXTERNAL DLASSQ >*/
/* .. */
/* .. Intrinsic Functions .. */
/*< INTRINSIC ABS, MAX, SQRT >*/
/* .. */
/* .. Executable Statements .. */
/*< IF( N.LE.0 ) THEN >*/
/* Parameter adjustments */
--e;
--d__;
/* Function Body */
if (*n <= 0) {
/*< ANORM = ZERO >*/
anorm = 0.;
/*< ELSE IF( LSAME( NORM, 'M' ) ) THEN >*/
} else if (lsame_(norm, "M", (ftnlen)1, (ftnlen)1)) {
/* Find max(abs(A(i,j))). */
/*< ANORM = ABS( D( N ) ) >*/
anorm = (d__1 = d__[*n], abs(d__1));
/*< DO 10 I = 1, N - 1 >*/
i__1 = *n - 1;
for (i__ = 1; i__ <= i__1; ++i__) {
/*< ANORM = MAX( ANORM, ABS( D( I ) ) ) >*/
/* Computing MAX */
d__2 = anorm, d__3 = (d__1 = d__[i__], abs(d__1));
anorm = max(d__2,d__3);
/*< ANORM = MAX( ANORM, ABS( E( I ) ) ) >*/
/* Computing MAX */
d__2 = anorm, d__3 = (d__1 = e[i__], abs(d__1));
anorm = max(d__2,d__3);
/*< 10 CONTINUE >*/
/* L10: */
}
/*< >*/
} else if (lsame_(norm, "O", (ftnlen)1, (ftnlen)1) || *(unsigned char *)
norm == '1' || lsame_(norm, "I", (ftnlen)1, (ftnlen)1)) {
/* Find norm1(A). */
/*< IF( N.EQ.1 ) THEN >*/
if (*n == 1) {
/*< ANORM = ABS( D( 1 ) ) >*/
anorm = abs(d__[1]);
/*< ELSE >*/
} else {
/*< >*/
/* Computing MAX */
d__3 = abs(d__[1]) + abs(e[1]), d__4 = (d__1 = e[*n - 1], abs(
d__1)) + (d__2 = d__[*n], abs(d__2));
anorm = max(d__3,d__4);
/*< DO 20 I = 2, N - 1 >*/
i__1 = *n - 1;
for (i__ = 2; i__ <= i__1; ++i__) {
/*< >*/
/* Computing MAX */
d__4 = anorm, d__5 = (d__1 = d__[i__], abs(d__1)) + (d__2 = e[
i__], abs(d__2)) + (d__3 = e[i__ - 1], abs(d__3));
anorm = max(d__4,d__5);
/*< 20 CONTINUE >*/
/* L20: */
}
/*< END IF >*/
}
/*< 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.;
/*< IF( N.GT.1 ) THEN >*/
if (*n > 1) {
/*< CALL DLASSQ( N-1, E, 1, SCALE, SUM ) >*/
i__1 = *n - 1;
dlassq_(&i__1, &e[1], &c__1, &scale, &sum);
/*< SUM = 2*SUM >*/
sum *= 2;
/*< END IF >*/
}
/*< CALL DLASSQ( N, D, 1, SCALE, SUM ) >*/
dlassq_(n, &d__[1], &c__1, &scale, &sum);
/*< ANORM = SCALE*SQRT( SUM ) >*/
anorm = scale * sqrt(sum);
/*< END IF >*/
}
/*< DLANST = ANORM >*/
ret_val = anorm;
/*< RETURN >*/
return ret_val;
/* End of DLANST */
/*< END >*/
} /* dlanst_ */
#ifdef __cplusplus
}
#endif
|
