"domain error: argument not in valid range"

[ilhanokan]

I have created my pipeline model and when I run my input, I encounter such an error;

WARNING BandGenLinLapackSolver: solve <> -LAPACK routine returned 14
domain error: argument not in valid range
while executing
"expr pow($lambda,0.5)"
invoked from within
"set omega [expr pow($lambda,0.5)]"
<file "projectinput2D3DOF.tcl" line 783>

What does it mean? How can I solve this problem?

[vesna]

How many inertial dofs to you have in your model?

[ilhanokan]

I have 3 inertial DOF for my model. X, Y and Rotational Z.

[vesna]

With the solver you use you can not ask for more than two eigenvalues. Check on this. If this is correct then it may be that your model has some instability issues.

[salehi]

Dear Vesna,

I've modeled a 2D frame on shallow foundation placed on a number of spring-damper elements (to model soil beneath foundation). My problem is with this line of my code:
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puts "First mode's period is [expr 2.*$PI/pow([eigen 1],0.5)]"
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I don't understand why when compiler reaches this line, displays this error and stops:
--------------
domain error: argument not in valid range
--------------
it's interesting that if I remove this line from my code, it'll work properly! Could you possibly help me with this, please? I'm looking forward to hearing from you. Thanks in advance.

Respectfully,
Salehi

[vesna]

Your expression looks good.

How many inertial DOFs do you have in your model?

[salehi]

Gee... you're very prompt! Actually I've already managed to resolve the problem. I don't know why the zero-length elements with two materials in two directions (one horizontal and the other one vertical to consider both horizontal and vertical stiffness of soil, simultaneously in one zero-length element) that I had defined weren't work properly and the frame was horizontally unstable! Finally, I was forced to define two groups of zero-length elements, each one for considering one direction's stiffness. Anyway, it seems that problem had been with the instability. Thanks a lot for your swift reply.

Truly,
Salehi