/*  -- translated by f2c (version 19940927).

   You must link the resulting object file with the libraries:

	-lf2c -lm   (in that order)

*/

#include "f2c.h"

/* Table of constant values */

static integer c__4 = 4;

static integer c__8 = 8;

static integer c__1 = 1;

/* Subroutine */ int slarot_(logical *lrows, logical *lleft, logical *lright, 

	integer *nl, real *c, real *s, real *a, integer *lda, real *xleft, 

	real *xright)

{

    /* System generated locals */

    integer i__1;

    /* Local variables */

    static integer iinc;

    extern /* Subroutine */ int srot_(integer *, real *, integer *, real *, 

	    integer *, real *, real *);

    static integer inext, ix, iy, nt;

    static real xt[2], yt[2];

    extern /* Subroutine */ int xerbla_(char *, integer *);

    static integer iyt;

/*  -- LAPACK auxiliary test routine (version 2.0) --   

       Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   

       Courant Institute, Argonne National Lab, and Rice University   

       February 29, 1992   

    Purpose   

    =======   

       SLAROT applies a (Givens) rotation to two adjacent rows or   

       columns, where one element of the first and/or last column/row   

       may be a separate variable.  This is specifically indended   

       for use on matrices stored in some format other than GE, so   

       that elements of the matrix may be used or modified for which   

       no array element is provided.   

       One example is a symmetric matrix in SB format (bandwidth=4), for 

       which UPLO='L':  Two adjacent rows will have the format:   

       row j:     *  *  *  *  *  .  .  .  .   

       row j+1:      *  *  *  *  *  .  .  .  .   

       '*' indicates elements for which storage is provided,   

       '.' indicates elements for which no storage is provided, but   

       are not necessarily zero; their values are determined by   

       symmetry.  ' ' indicates elements which are necessarily zero,   

        and have no storage provided.   

       Those columns which have two '*'s can be handled by SROT.   

       Those columns which have no '*'s can be ignored, since as long   

       as the Givens rotations are carefully applied to preserve   

       symmetry, their values are determined.   

       Those columns which have one '*' have to be handled separately,   

       by using separate variables "p" and "q":   

       row j:     *  *  *  *  *  p  .  .  .   

       row j+1:   q  *  *  *  *  *  .  .  .  .   

       The element p would have to be set correctly, then that column   

       is rotated, setting p to its new value.  The next call to   

       SLAROT would rotate columns j and j+1, using p, and restore   

       symmetry.  The element q would start out being zero, and be   

       made non-zero by the rotation.  Later, rotations would presumably 

       be chosen to zero q out.   

       Typical Calling Sequences: rotating the i-th and (i+1)-st rows.   

       ------- ------- ---------   

         General dense matrix:   

                 CALL SLAROT(.TRUE.,.FALSE.,.FALSE., N, C,S,   

                         A(i,1),LDA, DUMMY, DUMMY)   

         General banded matrix in GB format:   

                 j = MAX(1, i-KL )   

                 NL = MIN( N, i+KU+1 ) + 1-j   

                 CALL SLAROT( .TRUE., i-KL.GE.1, i+KU.LT.N, NL, C,S,   

                         A(KU+i+1-j,j),LDA-1, XLEFT, XRIGHT )   

                 [ note that i+1-j is just MIN(i,KL+1) ]   

         Symmetric banded matrix in SY format, bandwidth K,   

         lower triangle only:   

                 j = MAX(1, i-K )   

                 NL = MIN( K+1, i ) + 1   

                 CALL SLAROT( .TRUE., i-K.GE.1, .TRUE., NL, C,S,   

                         A(i,j), LDA, XLEFT, XRIGHT )   

         Same, but upper triangle only:   

                 NL = MIN( K+1, N-i ) + 1   

                 CALL SLAROT( .TRUE., .TRUE., i+K.LT.N, NL, C,S,   

                         A(i,i), LDA, XLEFT, XRIGHT )   

         Symmetric banded matrix in SB format, bandwidth K,   

         lower triangle only:   

                 [ same as for SY, except:]   

                     . . . .   

                         A(i+1-j,j), LDA-1, XLEFT, XRIGHT )   

                 [ note that i+1-j is just MIN(i,K+1) ]   

         Same, but upper triangle only:   

                      . . .   

                         A(K+1,i), LDA-1, XLEFT, XRIGHT )   

         Rotating columns is just the transpose of rotating rows, except 

         for GB and SB: (rotating columns i and i+1)   

         GB:   

                 j = MAX(1, i-KU )   

                 NL = MIN( N, i+KL+1 ) + 1-j   

                 CALL SLAROT( .TRUE., i-KU.GE.1, i+KL.LT.N, NL, C,S,   

                         A(KU+j+1-i,i),LDA-1, XTOP, XBOTTM )   

                 [note that KU+j+1-i is just MAX(1,KU+2-i)]   

         SB: (upper triangle)   

                      . . . . . .   

                         A(K+j+1-i,i),LDA-1, XTOP, XBOTTM )   

         SB: (lower triangle)   

                      . . . . . .   

                         A(1,i),LDA-1, XTOP, XBOTTM )   

    Arguments   

    =========   

    LROWS  - LOGICAL   

             If .TRUE., then SLAROT will rotate two rows.  If .FALSE.,   

             then it will rotate two columns.   

             Not modified.   

    LLEFT  - LOGICAL   

             If .TRUE., then XLEFT will be used instead of the   

             corresponding element of A for the first element in the   

             second row (if LROWS=.FALSE.) or column (if LROWS=.TRUE.)   

             If .FALSE., then the corresponding element of A will be   

             used.   

             Not modified.   

    LRIGHT - LOGICAL   

             If .TRUE., then XRIGHT will be used instead of the   

             corresponding element of A for the last element in the   

             first row (if LROWS=.FALSE.) or column (if LROWS=.TRUE.) If 

             .FALSE., then the corresponding element of A will be used.   

             Not modified.   

    NL     - INTEGER   

             The length of the rows (if LROWS=.TRUE.) or columns (if   

             LROWS=.FALSE.) to be rotated.  If XLEFT and/or XRIGHT are   

             used, the columns/rows they are in should be included in   

             NL, e.g., if LLEFT = LRIGHT = .TRUE., then NL must be at   

             least 2.  The number of rows/columns to be rotated   

             exclusive of those involving XLEFT and/or XRIGHT may   

             not be negative, i.e., NL minus how many of LLEFT and   

             LRIGHT are .TRUE. must be at least zero; if not, XERBLA   

             will be called.   

             Not modified.   

    C, S   - REAL   

             Specify the Givens rotation to be applied.  If LROWS is   

             true, then the matrix ( c  s )   

                                   (-s  c )  is applied from the left;   

             if false, then the transpose thereof is applied from the   

             right.  For a Givens rotation, C**2 + S**2 should be 1,   

             but this is not checked.   

             Not modified.   

    A      - REAL array.   

             The array containing the rows/columns to be rotated.  The   

             first element of A should be the upper left element to   

             be rotated.   

             Read and modified.   

    LDA    - INTEGER   

             The "effective" leading dimension of A.  If A contains   

             a matrix stored in GE or SY format, then this is just   

             the leading dimension of A as dimensioned in the calling   

             routine.  If A contains a matrix stored in band (GB or SB)   

             format, then this should be *one less* than the leading   

             dimension used in the calling routine.  Thus, if   

             A were dimensioned A(LDA,*) in SLAROT, then A(1,j) would   

             be the j-th element in the first of the two rows   

             to be rotated, and A(2,j) would be the j-th in the second,   

             regardless of how the array may be stored in the calling   

             routine.  [A cannot, however, actually be dimensioned thus, 

             since for band format, the row number may exceed LDA, which 

             is not legal FORTRAN.]   

             If LROWS=.TRUE., then LDA must be at least 1, otherwise   

             it must be at least NL minus the number of .TRUE. values   

             in XLEFT and XRIGHT.   

             Not modified.   

    XLEFT  - REAL   

             If LLEFT is .TRUE., then XLEFT will be used and modified   

             instead of A(2,1) (if LROWS=.TRUE.) or A(1,2)   

             (if LROWS=.FALSE.).   

             Read and modified.   

    XRIGHT - REAL   

             If LRIGHT is .TRUE., then XRIGHT will be used and modified   

             instead of A(1,NL) (if LROWS=.TRUE.) or A(NL,1)   

             (if LROWS=.FALSE.).   

             Read and modified.   

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

       Set up indices, arrays for ends   

       Parameter adjustments */

    --a;

    /* Function Body */

    if (*lrows) {

	iinc = *lda;

	inext = 1;

    } else {

	iinc = 1;

	inext = *lda;

    }

    if (*lleft) {

	nt = 1;

	ix = iinc + 1;

	iy = *lda + 2;

	xt[0] = a[1];

	yt[0] = *xleft;

    } else {

	nt = 0;

	ix = 1;

	iy = inext + 1;

    }

    if (*lright) {

	iyt = inext + 1 + (*nl - 1) * iinc;

	++nt;

	xt[nt - 1] = *xright;

	yt[nt - 1] = a[iyt];

    }

/*     Check for errors */

    if (*nl < nt) {

	xerbla_("SLAROT", &c__4);

	return 0;

    }

    if (*lda <= 0 || ! (*lrows) && *lda < *nl - nt) {

	xerbla_("SLAROT", &c__8);

	return 0;

    }

/*     Rotate */

    i__1 = *nl - nt;

    srot_(&i__1, &a[ix], &iinc, &a[iy], &iinc, c, s);

    srot_(&nt, xt, &c__1, yt, &c__1, c, s);

/*     Stuff values back into XLEFT, XRIGHT, etc. */

    if (*lleft) {

	a[1] = xt[0];

	*xleft = yt[0];

    }

    if (*lright) {

	*xright = xt[nt - 1];

	a[iyt] = yt[nt - 1];

    }

    return 0;

/*     End of SLAROT */

} /* slarot_ */