Warning in eigen value

[engnomran]

Hello every body
I use of OpenSees2.4.5-x64.exe and tcl/tk x64 8.5.16 for modeling.
But program has a error.
Error is in under commands:


proc Period_Ferequency 12
proc Period_Ferequency {Nmode} { ;

set pi 3.141592654 ;
set Landa [eigen $Nmode] ;(maybe erorr is in this line)????????????????????????????????????????????

for {set i 1} {$i <= $Nmode} {incr i 1} { ;

set T [expr 2*$pi/pow([lindex $Landa [expr $i-1]],0.5)] ;
set w [expr pow([lindex $Landa [expr $i-1]],0.5)] ;

puts "********************************************" ;
puts "T = $T sec " ;
puts " " ;
puts "w = $w rad/sec " ;
puts " " ;

} ;
} ;


What do I do for computation "eigen"


Link of error:
http://upload7.ir/uploads//54515ec6d808 ... 285fcb.png


please help me