[Scilab-users] Strange behaviour of eigs in new version 5.4

[Xuefeng LIU]

Dear users and developers of SCILAB,


I would to report two issues about eigs function in 5.4.

1) There come different results from spec and eigs. It seems that eigs give
false results.

The example:
-----------------------------------------
A=[ 1.   -0.5    0.   -0.5    0.    0.   ;
  -0.5    2.   -0.5    0.   -1.    0.   ;
    0.   -0.5    0.5    0.     0.    0.   ;
  -0.5    0.     0.     2.   -1.  -0.5  ;
    0.   -1.     0.   -1.     2.    0.   ;
    0.   0.     0.   -0.5    0.    0.5  ];
B=[
    0.0208333    0.0104167    0.           0.0104167    0.           0.         
    0.0104167    0.0625       0.0104167    0.0208333    0.0208333    0.         
    0.           0.0104167    0.0208333    0.           0.0104167    0.         
    0.0104167    0.0208333    0.           0.0625       0.0208333    0.0104167  
    0.           0.0208333    0.0104167    0.0208333    0.0625       0.0104167  
    0.           0.           0.           0.0104167    0.0104167    0.0208333 ];

eigs(A,B,3,"SM")
 ans  = 
    3.331D-16  
    13.120083  
    23.909112 

spec(A,B)
 ans  =
    126.48866  
    1.089D-15  
    31.225951  
    48.000134  
    84.284743  
    11.715411  
--------------------------------
Enviorment: MAC 10.7.4, SCILAB 5.4


2) On Ubuntu systems(3.2.0-32-generic-pae), the installation of SCILAB from the
package on SCILAB homepage has somethong wrong with the Arlnodi Package. The
executation of eigs gives error information on loading libsciarnoldi.so.


Xuefeng LIU