/*  -- translated by f2c (version 20100827).
   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"

/* Table of constant values */

static integer c__1 = 1;

doublereal splicingdlanst_(char *norm, integer *n, doublereal *d__, doublereal *e)
{
    /* 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 */
    static integer i__;
    static doublereal sum, scale;
    extern logical splicinglsame_(char *, char *);
    static doublereal anorm;
    extern /* Subroutine */ int splicingdlassq_(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   


    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.   

    =====================================================================   


       Parameter adjustments */
    --e;
    --d__;

    /* Function Body */
    if (*n <= 0) {
	anorm = 0.;
    } else if (splicinglsame_(norm, "M")) {

/*        Find max(abs(A(i,j))). */

	anorm = (d__1 = d__[*n], abs(d__1));
	i__1 = *n - 1;
	for (i__ = 1; i__ <= i__1; ++i__) {
/* Computing MAX */
	    d__2 = anorm, d__3 = (d__1 = d__[i__], abs(d__1));
	    anorm = max(d__2,d__3);
/* Computing MAX */
	    d__2 = anorm, d__3 = (d__1 = e[i__], abs(d__1));
	    anorm = max(d__2,d__3);
/* L10: */
	}
    } else if (splicinglsame_(norm, "O") || *(unsigned char *)
	    norm == '1' || splicinglsame_(norm, "I")) {

/*        Find norm1(A). */

	if (*n == 1) {
	    anorm = abs(d__[1]);
	} 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);
	    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);
/* L20: */
	    }
	}
    } else if (splicinglsame_(norm, "F") || splicinglsame_(norm, "E")) {

/*        Find normF(A). */

	scale = 0.;
	sum = 1.;
	if (*n > 1) {
	    i__1 = *n - 1;
	    splicingdlassq_(&i__1, &e[1], &c__1, &scale, &sum);
	    sum *= 2;
	}
	splicingdlassq_(n, &d__[1], &c__1, &scale, &sum);
	anorm = scale * sqrt(sum);
    }

    ret_val = anorm;
    return ret_val;

/*     End of DLANST */

} /* splicingdlanst_ */