Subroutine */
| 3185 | } /* sgeev_ */ |
| 3186 | |
| 3187 | /* Subroutine */ int sgehd2_(integer *n, integer *ilo, integer *ihi, real *a, |
| 3188 | integer *lda, real *tau, real *work, integer *info) |
| 3189 | { |
| 3190 | /* System generated locals */ |
| 3191 | integer a_dim1, a_offset, i__1, i__2, i__3; |
| 3192 | |
| 3193 | /* Local variables */ |
| 3194 | static integer i__; |
| 3195 | static real aii; |
| 3196 | extern /* Subroutine */ int slarf_(char *, integer *, integer *, real *, |
| 3197 | integer *, real *, real *, integer *, real *), xerbla_( |
| 3198 | char *, integer *), slarfg_(integer *, real *, real *, |
| 3199 | integer *, real *); |
| 3200 | |
| 3201 | |
| 3202 | /* |
| 3203 | -- LAPACK routine (version 3.2) -- |
| 3204 | -- LAPACK is a software package provided by Univ. of Tennessee, -- |
| 3205 | -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
| 3206 | November 2006 |
| 3207 | |
| 3208 | |
| 3209 | Purpose |
| 3210 | ======= |
| 3211 | |
| 3212 | SGEHD2 reduces a real general matrix A to upper Hessenberg form H by |
| 3213 | an orthogonal similarity transformation: Q' * A * Q = H . |
| 3214 | |
| 3215 | Arguments |
| 3216 | ========= |
| 3217 | |
| 3218 | N (input) INTEGER |
| 3219 | The order of the matrix A. N >= 0. |
| 3220 | |
| 3221 | ILO (input) INTEGER |
| 3222 | IHI (input) INTEGER |
| 3223 | It is assumed that A is already upper triangular in rows |
| 3224 | and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally |
| 3225 | set by a previous call to SGEBAL; otherwise they should be |
| 3226 | set to 1 and N respectively. See Further Details. |
| 3227 | 1 <= ILO <= IHI <= max(1,N). |
| 3228 | |
| 3229 | A (input/output) REAL array, dimension (LDA,N) |
| 3230 | On entry, the n by n general matrix to be reduced. |
| 3231 | On exit, the upper triangle and the first subdiagonal of A |
| 3232 | are overwritten with the upper Hessenberg matrix H, and the |
| 3233 | elements below the first subdiagonal, with the array TAU, |
| 3234 | represent the orthogonal matrix Q as a product of elementary |
| 3235 | reflectors. See Further Details. |
| 3236 | |
| 3237 | LDA (input) INTEGER |
| 3238 | The leading dimension of the array A. LDA >= max(1,N). |
| 3239 | |
| 3240 | TAU (output) REAL array, dimension (N-1) |
| 3241 | The scalar factors of the elementary reflectors (see Further |
| 3242 | Details). |
| 3243 | |
| 3244 | WORK (workspace) REAL array, dimension (N) |