Reply To: Stiffness matrix commands for student version

[blmcdona]

Thank you for your response.  Regarding commands, I actually used different commands to write the following code for stiffness and mass matrix:

 

 

 

*CFOPEN, stiffness_matrix.txt, TXT  ! Open a file for writing the stiffness matrix

 

/SOLU                     ! Switch to the solution environment

MAT, K, 1, STIFF  ! This will extract the global stiffness matrix

 

*DO, I, 1, 1000   ! Loop over matrix rows (adjust the number based on your model size)

    *DO, J, 1, 1000  ! Loop over matrix columns (adjust based on your model)

        *GET, Kij, MATRIX, I, J, STIFF  ! Get the stiffness matrix component K_ij

        *VWRITE, I, J, Kij

        (F10.5, F10.5, F10.5)  ! Format for writing the data

    *ENDDO

*ENDDO

 

*CFCLOS   ! Close the output file after writing the matrix

 

 

!Mass matrix

 

*CFOPEN, global_mass_matrix.txt, TXT  ! Open a text file for writing the mass matrix

 

/SOLU                     ! Switch to the solution environment

MAT, M, 1, MASS  ! Extract the global mass matrix

 

*DO, I, 1, 1000   ! Loop over matrix rows (adjust the number based on your model size)

    *DO, J, 1, 1000  ! Loop over matrix columns (adjust based on your model)

        *GET, Mij, MATRIX, I, J, MASS  ! Get the mass matrix component M_ij

        *VWRITE, I, J, Mij

        (F10.5, F10.5, F10.5)  ! Format for writing the data (adjust as needed)

    *ENDDO

*ENDDO

 

*CFCLOS  ! Close the output file after writing the matrix

 

However, the matrices are not square.  Instead, the only have three columns.  How do I make the matrices square?

 

Best,

Brandon