<div dir="ltr"><div class="gmail_quote"><div dir="ltr">On Mon, Oct 15, 2018 at 11:13 AM Yingjie Wu <<a href="mailto:yjwu16@gmail.com">yjwu16@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">Thank you very much, Matt.<br></div><div dir="ltr"><br></div><div dir="ltr">My problem is actually a two-dimensional problem, and the matrix in my binary file is actually a two-dimensional array, each point corresponding to a value on the two-dimensional grid. </div></div></div></div></blockquote><div><br></div><div>These are still vectors. Vec store fields, which gives values to points on your grid. Matrices map between states, so between vectors.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">Your suggestion is very useful to me. I can try to convert the matrix binary file into a vector binary file to give program an initial value. So what I should do is: </div><div dir="ltr">1. establish parallel vectors. </div><div dir="ltr"> 2. reads data from binary files to vectors. (VecLoad()) </div><div dir="ltr">3. use VecGetArray() in FormInitialGuess() to use vector elements to give the initial values of the field variables. </div><div dir="ltr">I know DM can support parallel computing (domain decomposition). How can I ensure that the part of the vector built on each processor corresponds to the index of DM object? (Cause my field variables are established by DMDACreate2d, and I want to assign initial values to field variables using read vectors )<br></div></div></div></div></blockquote><div><br></div><div>Yes. Many times you will want to VecLoad, then DMGlobalToLocal() to get ghosted vectors, then DMVecGetArray() to get ghosted arrays.</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"></div><div dir="ltr"><br></div><div>Thanks,</div><div>Yingjie</div></div></div></div><br><div class="gmail_quote"><div dir="ltr">Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>> 于2018年10月15日周一 下午10:52写道：<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_quote"><div dir="ltr">On Mon, Oct 15, 2018 at 10:42 AM Yingjie Wu <<a href="mailto:yjwu16@gmail.com" target="_blank">yjwu16@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>Dear Petsc developer: </div><div>Hi,</div><div>Thank you very much for your previous reply. </div><div>I recently wanted to modify my program to parallel version, and encountered some problems in modifying it. </div><div>1. There are functions (read matrix) in the program that reads files,will they affect my parallelism? </div></div></div></div></div></blockquote><div><br></div><div>No, MatLoad works in parallel. This will work unchanged if you want the default layout. If you want a special partition,</div><div>you must call MatSetSizes() after MatCreate().</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div> The codes are as follows: </div></div></div><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div><div><div><font size="1">ierr = PetscViewerBinaryOpen (PETSC_COMM_WORLD, file, FILE_MODE_READ, &viewer); CHKERRQ (ierr); </font></div></div></div><div><div><div><font size="1">ierr = MatCreate (PETSC_COMM_WORLD, &A1); CHKERRQ (ierr); </font></div></div></div><div><div><div><font size="1">ierr = MatSetFromOptions (A1); CHKERRQ (ierr); </font></div></div></div><div><div><div><font size="1">ierr = MatCreate (PETSC_COMM_WORLD, &A2); CHKERRQ (ierr); </font></div></div></div><div><div><div><font size="1">ierr = MatSetFromOptions (A2); CHKERRQ (ierr); </font></div></div></div><div><div><div><font size="1">ierr = MatLoad (A1, viewer); CHKERRQ (ierr); </font></div></div></div><div><div><div><font size="1">ierr = MatLoad (A2, viewer); CHKERRQ (ierr); </font></div></div></div><div><div><div><font size="1">ierr = PetscViewerDestroy (&viewer); CHKERRQ (ierr); </font> </div></div></div></blockquote><div dir="ltr"><div dir="ltr"><div>I read two matrix information from a binary file and wanted to use it on each processor (in fact, my goal was to use these two matrices to give initial values to the two field variables). The program can run in serial time. Now I want to change it to parallel program. What do I need to modify? </div><div>2. Following the last question, I used the following code in giving initial value procedure FormInitialGuess(): </div></div></div></div><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div><div><div><div><font size="1">ierr = MatSeqAIJGetArray (A1, &initial_phi1); CHKERRQ (ierr); </font></div></div></div></div><div><div><div><div><font size="1">ierr = MatSeqAIJGetArray (A2, &initial_phi2); CHKERRQ (ierr); </font> </div></div></div></div></blockquote><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>I found this function on manualpages, and I felt that it could fulfill my need to represent the elements of the matrix in arrays to give field variables an initial value in each grid. The matrix A1 and A2 above are actually the matrix information that was read from the file before. Now I want to modify it as a parallel program. How do I use matrix information to give initial values in parallel? (In p<span style="white-space:pre-wrap">rogram, field variables are implemented through DM because parallel computing and Ghost Value are supported</span>)</div></div></div></div></div></blockquote><div><br></div><div>I do not understand the use of matrices to initialize field values. Usually field values are stored on Vec objects, and this is</div><div>the philosophy of DM objects.</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>Thanks,</div><div>Yingjie</div></div></div></div></div>
</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="m_4241219980156490423m_-5482560187335229898gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener</div><div><br></div><div><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br></div></div></div></div></div></div></div></div>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener</div><div><br></div><div><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br></div></div></div></div></div></div></div></div>