Skip to main content

Matrix Transfer between MATLAB and Ansys

Matrix Transfer*

Reading and writing matrix or arrays to MATLAB and back can be painstaking as described by SimuTech in a well written article using *TREAD or *VREAD. Wouldn't it be great to have someone else do the heavy lifting for you on formatting etc?

Fortunately there is a Matrix Market format sponsored by NIST that is also supported by Ansys and Matlab. There are two very useful MATLAB functions created just for this purpose:

  • mmread.m  for reading in the Market Matrix file into MATLAB
  • mmwrite.m for writing the matrix into a Matrix Market file

Writing Matrix or Arrays from Ansys to be Read by MATLAB
In Ansys...
/prep7
*dim, c,, 10,10, 1 ! Example Matrix
enow = 0
*do, ct, 1, 10        
    *do, ct2, 1, 10
        c(ct,ct2) = ct*ct2
    *enddo    
*enddo    

 !!! Writes out Matrix to matlab
*dmat, exportmatrix, D, import, APDL, c ! export to matrix file
*export, exportmatrix, mmf, mytemp.mtx

In MATLAB, the command is simply...
c = mmread('mytemp.mtx'); % mmread.m must is in working directory

Writing Matrix from MATLAB to be Read by Ansys
In MATLAB...
m = transpose(1:10) * (1:10);  % example matrix
mmwrite('toansys.mtx', m, 'example matrix');  % writes out matrix 

In Ansys...
*dmat, importmatrix, d, import, mmf, toansys.mtx ! imports 
*dim, fromMatlab, array, 10, 10 ! pre-define matrix size
*export, importmatrix, apdl, fromMatlab, 1, 10 
! writes out to apdl named fromMatlab, 1st column to 10th column

You may now access the matrix in Ansys for example via...
q = fromMatlab(3, 4) 
*stat, q

 Other Comments
The Harwell-Boeing format can also be an alternative that is also supported by *EXPORT. It might come in handy for large sparse matrix though I've not tried it myself. 
Labels:

Comments

Post a Comment

Popular posts from this blog

ANSYS User Defined Results

There is an abundant of options in ANSYS classic when one wishes to post process results. ANSYS workbench default pull down menu post processing options are more limited but they can still be accessed via the User Defined Results. One way not commonly used but can come in handy is as follows: Zeroth: Under Analysis Settings, there is "Output Controls" where you can toggle to "Yes" what you would like to save before the solution starts. This is like OUTRES in APDL. Output Controls First: After solving the model, click on Solution in the tree to highlight it. Solution Second: Click on Worksheet in the toolbar. Worksheet Third: In the worksheet, you will see list of results that are saved. Right click on it to create the User Defined Results. Create User Defined Results So here we have it. You could of look up the different expressions in the help document but I find this method of accessing the results convenient.  Example: Aspec...
1 comment
Read more

Export Stiffness Matrix from Ansys

It is sometimes useful to extract the mass and stiffness matrix from Ansys.     *SMAT, MatK, D, IMPORT, FULL, file.full, STIFF       *PRINT, matk, matk, txt Exporting mass matrix would be similar:       *SMAT, MatM, D, import, full, file.full, MASS The above script uses APDL Math to get the job done. (Please see previous post for another example). The ordering of the matrix is unfortunately not concurrently exported. To verify the sequencing is as expected, we will work to replicate a truss example in the  Finite Element Trusses course notes by Bob Greenlee. Figure 1: Truss Problem Setup Model Creation Script to create model: /prep7 !! Creates Model to reflect course notes ! Properties et ,1,1  mp , ex, 1, 29.5e6 r , 1, 1 ! Geometry n ,1 $  n ,2, 40 $  n ,3, 40, 30 $  n ,4, 0, 30 e ,1,2 $  e ,2,3 $  e ,1,3 $  e ,3,4 ! Boundary Conditions d ,1,ux,0 $  d ,1,uy,0 d ,2,uy...
43 comments
Read more

ANSYS APDL Syntax Highlighting editor

Notepad++ with APDL User Defined Language The editor of my choice is Notepad++  with the available User Defined Language Files for APDL. You can install it without administrative privileges via the zip file. The best part of it is, it's FREE! After installing Notepad++, go to "Language>Define Your Language..." then "Import" the XML file downloaded from the above link. Remember to restart Notepad++ so that the language changes will take into effect. Opening up any *.inp or *.ans files should automatically switch highlighting to APDL. I made some minor edits. Here's my XML file: LINK . I also heard Sublime Text and  Ultraedit  has more advance features but they aren't (totally) free.
9 comments
Read more