# [Scilab-users] Spec function Classic List Threaded 3 messages Open this post in threaded view
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## [Scilab-users] Spec function This question is about how to use the spec function to calculate eigenvalues. Suppose a square matrix D is a function of real number b. I am trying to find the eigenvalues of D for various b with the spec function. When I calculate for b = 1 and 3 simultaneously with the attached code, I get all eigenvalues for b = 1 are 0. However, I calculate for b = 1 alone , I get an eigenvalue of -0.5 ± 4.97i and 0 otherwise. Why are the results of the two methods different? Is the usage of the spec function wrong? Which result is correct? Best regards testSpec.sce   -- Sent from: http://mailinglists.scilab.org/Scilab-users-Mailing-Lists-Archives-f2602246.html_______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users Hi, In the sample code provided, the loops 'for j=length(b_V)', seem to only evaluate the case b=3. It does not seem to match the explanation below. Regards, Rafael From: users <[hidden email]> On Behalf Of fujimoto2005 Sent: Friday, May 22, 2020 4:06 PM To: [hidden email] Subject: [Scilab-users] Spec function This question is about how to use the spec function to calculate eigenvalues. Suppose a square matrix D is a function of real number b. I am trying to find the eigenvalues of D for various b with the spec function. When I calculate for b = 1 and 3 simultaneously with the attached code, I get all eigenvalues for b = 1 are 0. However, I calculate for b = 1 alone , I get an eigenvalue of -0.5 ± 4.97i and 0 otherwise. Why are the results of the two methods different? Is the usage of the spec function wrong? Which result is correct? Best regards testSpec.sce   _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users Dear Rafael,Thanks for your reply.You are  right.It's due to my wrong code.Best regards,Masahiro Fujimoto2020年5月25日(月) 15:18 Rafael Guerra <[hidden email]>:Hi, In the sample code provided, the loops 'for j=length(b_V)', seem to only evaluate the case b=3. It does not seem to match the explanation below. Regards, Rafael From: users <[hidden email]> On Behalf Of fujimoto2005 Sent: Friday, May 22, 2020 4:06 PM To: [hidden email] Subject: [Scilab-users] Spec function This question is about how to use the spec function to calculate eigenvalues. Suppose a square matrix D is a function of real number b. I am trying to find the eigenvalues of D for various b with the spec function. When I calculate for b = 1 and 3 simultaneously with the attached code, I get all eigenvalues for b = 1 are 0. However, I calculate for b = 1 alone , I get an eigenvalue of -0.5 ± 4.97i and 0 otherwise. Why are the results of the two methods different? Is the usage of the spec function wrong? Which result is correct? Best regards testSpec.sce   _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users