Le Vendredi 26 Juin 2015 11:16 CEST, "Carrico, Paul"
<[email protected]> a écrit:
> Hi Antoine,
>
> Thanks for the comments; In attachment the results of the calculations (note
> that the modal effective depends on the eigenvectors)
>
> The calculation for the difference calculations are described herebellow ..
I'm confused, who's who:
u = value or vector
v = value or vector ?
Antoine
>
>
> Paul
>
> ###################################################################################"
> // prog principal
> nbre = 10;
> for k = 1 : nbre
> printf("\n*******\nIteration num %d\n",k);
> s1 = " ...
> [u" + string(k) + ",v" + string(k) + ",K" + string(k) + ",M" + string(k)
> + "] = calcul_v() , ...
> [nl,nc] = size(v" + string(k) + ") , ...
> save(''u" + string(k) + ".bin'',''u" + string(k) + "'') , ...
> save(''v" + string(k) + ".bin'',''v" + string(k) + "'') , ...
> clear nl , ...
> clear nc , ...
> save(''K" + string(k) + ".bin'',''K" + string(k) + "'') , ...
> save(''M" + string(k) + ".bin'',''M" + string(k) + "'') , ...
> ";
> execstr(s1) ;
>
> end
>
> printf("\n\n");
>
> // difference v1 - v2
> for k = 2 : nbre
> s2 = " ...
> printf(""(eigenvalues) Max delta u%d - u1 = %g\n"",k,abs(max(u" +
> string(k) + " - u1))) , ...
> printf(""(eigenvectors) Max delta v%d - v1 = %g\n"",k,abs(max(v" +
> string(k) + " - v1))) , ...
> printf(""(input matrix) Max delta K%d - K1 = %g\n"",k,abs(max(K" +
> string(k) + " - K1))) , ...
> printf(""(input matrix) Max delta M%d - M1 = %g\n"",k,abs(max(M" +
> string(k) + " - M1))) , ...
> ";
> execstr(s2) ;
> printf("\n");
> end
> ######################################################################################"
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> -----Message d'origine-----
> De : users [mailto:[email protected]] De la part de Antoine
> Monmayrant Envoyé : vendredi 26 juin 2015 10:50 À : International users
> mailing list for Scilab.
> Objet : Re: [Scilab-users] eigs calculation
>
> Hi Paul,
>
> I don't really like a function that gives different answers for the very same
> input.
> That sounds like a bug to me.
> That being said, from the data you showed, it is not clear that your
> eigenvector are really different.
> If what you show is just a difference in the norm of the difference between
> the eigenvalue at iteration 1 and N, that might be OK.
> Indeed, if v is an eigenvector, a.v with a non zero-scalar, is also an
> eigenvector.
> You should check whether v1 and vN are colinear: if they are, the results are
> not really different, they just differ by a scaling factor.
> But I would still call it a bug, as a function should always give the same
> answer when given the same input parameters.
>
> Cheers,
>
> Antoine
>
>
> Le Jeudi 25 Juin 2015 17:17 CEST, "Carrico, Paul"
> <[email protected]> a écrit:
>
> > Dear all
> >
> > I'm still working on my "eigs" issue topic and I'm still trying to
> > understand what's going wrong;
> >
> > I run a test case :
> > - same function is launched 10 times
> > - each time the input data are recorded (K,M)
> > - for each loop the eigenvalues u and the eigenvectors v are recorded
> >
> > Then the values of each loop are compared with the values of the loop
> > 1
> >
> > If K,M,u remains strictly identical, it is not the case for u (the
> > eigenvectors) ... why ?
> >
> > I've ever check any initialization issue, but everything seems to be
> > ok
> >
> > Paul
> >
> > PS : the results of this case
> >
> > Max delta v2 - v1 = 453.857
> > Max delta K2 - K1 = 0
> > Max delta M2 - M1 = 0
> >
> > Max delta v3 - v1 = 549.214
> > Max delta K3 - K1 = 0
> > Max delta M3 - M1 = 0
> >
> > Max delta v4 - v1 = 585.95
> > Max delta K4 - K1 = 0
> > Max delta M4 - M1 = 0
> >
> > Max delta v5 - v1 = 379.702
> > Max delta K5 - K1 = 0
> > Max delta M5 - M1 = 0
> >
> > Max delta v6 - v1 = 489.844
> > Max delta K6 - K1 = 0
> > Max delta M6 - M1 = 0
> >
> > Max delta v7 - v1 = 439.221
> > Max delta K7 - K1 = 0
> > Max delta M7 - M1 = 0
> >
> > Max delta v8 - v1 = 432.406
> > Max delta K8 - K1 = 0
> > Max delta M8 - M1 = 0
> >
> > Max delta v9 - v1 = 351.752
> > Max delta K9 - K1 = 0
> > Max delta M9 - M1 = 0
> >
> > Max delta v10 - v1 = 554.515
> > Max delta K10 - K1 = 0
> > Max delta M10 - M1 = 0
> >
> > -----Message d'origine-----
> > De : Carrico, Paul
> > Envoyé : mercredi 17 juin 2015 22:18
> > À : International users mailing list for Scilab.
> > Objet : RE: [Scilab-users] eigs calculation
> >
> > Dear All
> >
> > Thanks for the answers.
> >
> > To give more information's on what I'm doing (That's quite new I confess),
> > I'm performing a (basic) finite element calculation with beams using
> > sparse matrix (stiffness matrix K and mass matrix M).
> > [u,v] =
> > eigs(K((ddl_elem+1):$,(ddl_elem+1):$),M((ddl_elem+1):$,(ddl_elem+1):$)
> > ,n,"SM");
> >
> > Nota: ddl means dof
> >
> > I'm calculated first the natural frequencies using (K - omega^2.M).x=0 ...
> > the pulse (or circular frequencies) are no more and no less than the
> > eigenvalues of the above system (u = omega^2).
> >
> > Just a "mechanical" remark: since the beam is clamped in one side (and free
> > on the tip), it is absolutely normal that you find twice the same natural
> > frequency (1rst mode in one direction, the second one in a new direction at
> > 90°) .... I've been really surprised to find it, but happy at the same time
> > ...
> >
> > The origin of my question was: since it obvious that the results are
> > strongly sensitive to the "units" (i.e. the numbers), I'm wondering if
> > there is a way to control the accuracy of the eigenvalues calculation using
> > eigs keywords ...
> >
> > In any way, thanks for the debate
> >
> > Paul
> >
> > EXPORT CONTROL :
> > Cet email ne contient pas de données techniques This email does not
> > contain technical data _______________________________________________
> > users mailing list
> > [email protected]
> > https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.scilab.org_m
> > ailman_listinfo_users&d=AwIGaQ&c=0hKVUfnuoBozYN8UvxPA-w&r=4TCz--8bXfJh
> > ZZvIxJAemAJyz7Vfx78XvgYu3LN7eLo&m=1q3UvWvNm8K7-IZGCUzIV3uKngKalGVN-2TH
> > izNu_Ek&s=Qd7_9c6GV5rmRHnsvDdDgvnnodut0J24q0KOnk1zqb8&e=
> >
>
>
>
>
>
>
> _______________________________________________
> users mailing list
> [email protected]
> https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.scilab.org_mailman_listinfo_users&d=AwIGaQ&c=0hKVUfnuoBozYN8UvxPA-w&r=4TCz--8bXfJhZZvIxJAemAJyz7Vfx78XvgYu3LN7eLo&m=1q3UvWvNm8K7-IZGCUzIV3uKngKalGVN-2THizNu_Ek&s=Qd7_9c6GV5rmRHnsvDdDgvnnodut0J24q0KOnk1zqb8&e=
>
>
> EXPORT CONTROL :
> Cet email ne contient pas de données techniques
> This email does not contain technical data
_______________________________________________
users mailing list
[email protected]
http://lists.scilab.org/mailman/listinfo/users
