Re: [Scilab-users] number od decimals with csvWrite
The simplest way is to use round A=rand(3,3); B=round(100*A)/100; Serge Steer Le 25/06/2015 22:07, Simone Meroni a écrit : Hi I want to write some data and export them with csvWrite I need to have no more than 2 decimals for aesthetic reasons. How can I set the number of decimals? Thanks, Simone Meroni ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
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 paul.carr...@esterline.com 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 users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
Re: [Scilab-users] eigs calculation
U = eigenvalues - matrix (nx1)
V = eigenvectors - matrix (nxn)
NB: n = 12 since I'm foccusing of the n first natural frequencies
Paul
-Message d'origine-
De : users [mailto:users-boun...@lists.scilab.org] De la part de Antoine
Monmayrant Envoyé : vendredi 26 juin 2015 12:26 À : International users mailing
list for Scilab.
Objet : Re: [Scilab-users] eigs calculation
Le Vendredi 26 Juin 2015 11:16 CEST, Carrico, Paul
paul.carr...@esterline.com 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:users-boun...@lists.scilab.org] 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
paul.carr...@esterline.com 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] =
