The OpenNET Project / Index page

[ новости /+++ | форум | теги | ]

Интерактивная система просмотра системных руководств (man-ов)

 ТемаНаборКатегория 
 
 [Cписок руководств | Печать]

slag2 (3)
  • >> slag2 (3) ( Solaris man: Библиотечные вызовы )
  • 
    NAME
         slag2 - compute the eigenvalues  of  a  2  x  2  generalized
         eigenvalue  problem A-wB, with scaling as necessary to avoid
         overflow/underflow
    
    SYNOPSIS
         SUBROUTINE SLAG2( A, LDA, B, LDB,  SAFMIN,  SCALE1,  SCALE2,
                   WR1, WR2, WI )
    
         INTEGER LDA, LDB
    
         REAL SAFMIN, SCALE1, SCALE2, WI, WR1, WR2
    
         REAL A( LDA, * ), B( LDB, * )
    
    
    
         #include <sunperf.h>
    
         void slag2(float *sa, int lda, float  *sb,  int  ldb,  float
                   safmin,  float *scale1, float *scale2, float *wr1,
                   float *wr2, float *wi) ;
    
    PURPOSE
         SLAG2 computes the eigenvalues of a 2 x 2 generalized eigen-
         value  problem   A - w B, with scaling as necessary to avoid
         over-/underflow.
    
         The scaling factor "s"  results  in  a  modified  eigenvalue
         equation
    
             s A - w B
    
         where  s  is a non-negative scaling factor  chosen  so  that
         w,   w B, and  s A  do not overflow and, if possible, do not
         underflow, either.
    
    
    ARGUMENTS
         A         (input) REAL array, dimension (LDA, 2)
                   On entry, the 2 x 2 matrix A.  It is assumed  that
                   its  1-norm  is  less than 1/SAFMIN.  Entries less
                   than sqrt(SAFMIN)*norm(A)  are  subject  to  being
                   treated as zero.
    
         LDA       (input) INTEGER
                   The leading dimension of the array A.  LDA >= 2.
    
         B         (input) REAL array, dimension (LDB, 2)
                   On entry, the 2 x 2 upper triangular matrix B.  It
                   is  assumed  that  the  one-norm of B is less than
                   1/SAFMIN.   The  diagonals  should  be  at   least
                   sqrt(SAFMIN)  times  the  largest element of B (in
                   absolute value); if a  diagonal  is  smaller  than
                   that,  then  +/- sqrt(SAFMIN) will be used instead
                   of that diagonal.
    
         LDB       (input) INTEGER
                   The leading dimension of the array B.  LDB >= 2.
    
         SAFMIN    (input) REAL
                   The smallest positive number  s.t.  1/SAFMIN  does
                   not  overflow.  (This should always be SLAMCH('S')
                   -- it is an argument in order to avoid  having  to
                   call SLAMCH frequently.)
    
         SCALE1    (output) REAL
                   A scaling factor used to avoid over-/underflow  in
                   the  eigenvalue  equation  which defines the first
                   eigenvalue.  If the eigenvalues are complex,  then
                   the  eigenvalues  are  ( WR1  +/-  WI i ) / SCALE1
                   (which may lie outside the exponent range  of  the
                   machine), SCALE1=SCALE2, and SCALE1 will always be
                   positive.  If the eigenvalues are real,  then  the
                   first  (real)  eigenvalue  is   WR1 / SCALE1 , but
                   this may  overflow  or  underflow,  and  in  fact,
                   SCALE1  may  be  zero  or  less than the underflow
                   threshhold if the exact eigenvalue is sufficiently
                   large.
    
         SCALE2    (output) REAL
                   A scaling factor used to avoid over-/underflow  in
                   the  eigenvalue  equation which defines the second
                   eigenvalue.  If the eigenvalues are complex,  then
                   SCALE2=SCALE1.   If the eigenvalues are real, then
                   the second (real) eigenvalue is WR2 / SCALE2 , but
                   this  may  overflow  or  underflow,  and  in fact,
                   SCALE2 may be zero  or  less  than  the  underflow
                   threshhold if the exact eigenvalue is sufficiently
                   large.
    
         WR1       (output) REAL
                   If the eigenvalue is  real,  then  WR1  is  SCALE1
                   times  the eigenvalue closest to the (2,2) element
                   of A B**(-1).  If the eigenvalue is complex,  then
                   WR1=WR2  is  SCALE1  times  the  real  part of the
                   eigenvalues.
    
         WR2       (output) REAL
                   If the eigenvalue is  real,  then  WR2  is  SCALE2
                   times  the other eigenvalue.  If the eigenvalue is
                   complex, then WR1=WR2 is  SCALE1  times  the  real
                   part of the eigenvalues.
    
         WI        (output) REAL
                   If the eigenvalue is real, then WI  is  zero.   If
                   the eigenvalue is complex, then WI is SCALE1 times
                   the imaginary part of the  eigenvalues.   WI  will
                   always be non-negative.
    
    
    
    


    Поиск по тексту MAN-ов: 




    Партнёры:
    PostgresPro
    Inferno Solutions
    Hosting by Hoster.ru
    Хостинг:

    Закладки на сайте
    Проследить за страницей
    Created 1996-2024 by Maxim Chirkov
    Добавить, Поддержать, Вебмастеру