<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div></div><div><br></div><div><br>El 14 sept 2018, a las 17:45, Jan Grießer <<a href="mailto:griesser.jan@googlemail.com">griesser.jan@googlemail.com</a>> escribió:<br><br></div><blockquote type="cite"><div><div dir="ltr"><div dir="ltr"><div dir="ltr">Hey there,<div>first i want to say thanks to <span style="color:rgb(0,0,0);white-space:pre-wrap"><span class="" id=":1br.1" tabindex="-1" style="">Satish</span> and </span><font color="#000000"><span style="white-space:pre-wrap">Matt for helping with with my last problem with the <span class="" id=":1br.2" tabindex="-1" style="">mpi</span> compilation. I have two <span class="" id=":1br.3" tabindex="-1" style="">questions</span> related to solving a big, <span class="" id=":1br.4" tabindex="-1" style="">hermitian</span>, standard eigenvalue problem using SLEPc4py., compiled with Intel <span class="" id=":1br.5" tabindex="-1" style="">MKL</span> and Intel <span class="" id=":1br.7" tabindex="-1" style="">MPI</span>. </span></font><font color="#000000"><span style="white-space:pre-wrap">
- I am using slepc4py with <span class="" id=":1br.8" tabindex="-1" style="">mpi</span> and run it with around -n 20 cores at the moment and how i wanted to ask if there is an easy way to retrieve the <span class="" id=":1br.9" tabindex="-1" style="">eigenvectors</span>? When i run my code and print </span></font>
<font color="#000000"><span style="white-space:pre-wrap">for i in range(<span class="" id=":1br.10" tabindex="-1" style="">nconv</span>):</span></font></div><div><font color="#000000"><span style="white-space:pre"> </span>for i in range(<span class="" id=":1br.11" tabindex="-1" style="">nconv</span>):<span style="white-space:pre-wrap">
val = E.<span class="" id=":1br.12" tabindex="-1" style="">getEigenpair</span>(i, <span class="" id=":1br.13" tabindex="-1" style="">vr</span>, vi)
Print(<span class="" id=":1br.14" tabindex="-1" style="">vr</span>.<span class="" id=":1br.15" tabindex="-1" style="">getArray</span>())</span></font>
</div><div><font color="#000000"><span style="white-space:pre-wrap"> i get the parts of the <span class="" id=":1br.16" tabindex="-1" style="">eigenvectors</span> according to the partition of the matrix. Is there any easy way to put them together in an array and write them to file ? (I am struggling a little bit with the building them in the correct order)</span></font></div></div></div></div></div></blockquote><div><br></div><div>You need <a name="VecScatterCreateToZero"><h1 style="display: inline !important;"><font color="#000000"><span style="font-size: 19px; background-color: rgba(255, 255, 255, 0);">VecScatterCreateToZero. </span></font></h1></a>There must be an equivalent in python.</div><div><br></div><blockquote type="cite"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div><font color="#000000"><span style="white-space:pre-wrap">- I need to solve eigenvalue problems up to a dimension of 100000 degrees of freedom and i need all eigenvalues and <span class="" id=":1br.17" tabindex="-1" style="">eigenvectors</span>. I think solving all eigenvalues in one process is far too much and i thought about if it is possible to apply the spectrum slicing described in Chap. 3.4.5. Due to the nature of my problem, i am able to simulate smaller systems of 10000 <span class="" id=":1br.18" tabindex="-1" style="">DOF</span> and extract the biggest eigenvalue, which will be the same for larger systems sizes. Is this in general possible since i have a standard HEP problem or is there a better and faster <span class="" id=":1br.20" tabindex="-1" style="">possibility</span> to do this?</span></font></div></div></div></div></div></blockquote><div><br></div><div>In general, SLEPc is not intended for computing the whole spectrum. You can try with spectrum slicing but this will be competitive if computing just a percentage of eigenvalues, 50% say. </div><div><br></div><div>Jose</div><br><blockquote type="cite"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div><font color="#000000"><span style="white-space:pre-wrap"><br></span></font></div><div><font color="#000000"><span style="white-space:pre-wrap">Thank you very much!</span></font></div></div></div></div>
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