[julia-users] Re: Error calculating eigs of pentadiagonal matrix.

2016-11-02 Thread Alejandro Castellanos
As of now, I'm leaning towards maybe my feeding the matrix some Inf values due to the grid spacing I'm using but I'm not sure. Would it help if I uploaded the whole of my code, in here? Mind you, the comments are in Spanish... Cheers. El miércoles, 2 de noviembre de 2016, 3:43:48 (UTC-7), Alej

[julia-users] Re: Error calculating eigs of pentadiagonal matrix.

2016-11-02 Thread Steven G. Johnson
On Wednesday, November 2, 2016 at 1:40:17 PM UTC-4, Ralph Smith wrote: > > Eigs uses shift-and-invert for the :sm variant, so it tries to solve M x = > b. Try adding a small sigma parameter. > Yes, but it really should be able to handle matrices with a nontrivial nullspace ... the nullspace is

[julia-users] Re: Error calculating eigs of pentadiagonal matrix.

2016-11-02 Thread Ralph Smith
Eigs uses shift-and-invert for the :sm variant, so it tries to solve M x = b. Try adding a small sigma parameter.

[julia-users] Re: Error calculating eigs of pentadiagonal matrix.

2016-11-02 Thread Alejandro Castellanos
Hi, Steven. This is how I'm building the matrix: #==# # OPERATING THE MATRIX # #==# # --Creating HAMILTONIAN container. M = spzeros(n*n, n*n)#--Creating the SPARSE matrix (n is the number of points per row). # --Working kinetic energy int

[julia-users] Re: Error calculating eigs of pentadiagonal matrix.

2016-11-02 Thread Steven G. Johnson
On Wednesday, November 2, 2016 at 9:48:38 AM UTC-4, Steven G. Johnson wrote: > > > > On Wednesday, November 2, 2016 at 6:43:48 AM UTC-4, Alejandro Castellanos > wrote: >> >> I use this command: *l, v = eigs(M,nev=15,which = :SM ,ritzvec=true)* >> > > How are you constructing the matrix M? > > A

[julia-users] Re: Error calculating eigs of pentadiagonal matrix.

2016-11-02 Thread Steven G. Johnson
On Wednesday, November 2, 2016 at 6:43:48 AM UTC-4, Alejandro Castellanos wrote: > > I use this command: *l, v = eigs(M,nev=15,which = :SM ,ritzvec=true)* > How are you constructing the matrix M? Apparently eigs thinks that your matrix is symmetric positive-definite (SPD), because it is tryi

[julia-users] Re: Error calculating eigs of pentadiagonal matrix.

2016-11-02 Thread Jeffrey Sarnoff
I have one suggestion: see if Andreas' LinearAlgebra.jl does any better. Pkg.clone(""https://github.com/andreasnoack/LinearAlgebra.jl";) using LinearAlgebra # ... If there is still difficulty, you may look at eigenGeneral.jl