SYMPTOM/PROBLEM
---------------
How to output the stiffness matrix and/or the mass matrix from I-deas Model 
Solution?

SOLUTION/WORKAROUND
-------------------
Storing and Accessing Elemental Stiffness and Mass Matrices

In the past this has been difficult, as the only option was to modify a 
program file to use a different setup method and then do a hypermatrix write 
to a universal file. 
Begining with I-deas 8 and in all subsequent releases of I-deas and I-deas NX 
Series, there is a delivered program file nbbstf.prg which can be copied 
locally and made to be a user defined program file in either a linear statics 
or normal mode analysis. The program file will be found in the 
$SDRC_INSTL/ideas/stb directory.  The selection to specify a user defined 
program file is chosen under the Options when creating a Solution Set.	
Running with this program file will not perform a "solve" but just generate 
the matrices and write them to the files modelfile.stf and modelfile.mas.  
These files will be written to the directory I-deas is started in. 

Rather than give a specification of the file format, shown below are Fortran 
and C sample programs which read these files and print out the contents. These programs can be used to read both the modelfile.stf file and the modelfile.mas file.  A programmer could also alter the code to specify any desired format.



Fortran version: 


C     SAMPLE PROGRAM FOR READING THE ELEMENT MATRICES GENERATED 

C     IN MODEL SOLUTION
C
      INTEGER IUNIT
      PARAMETER (IUNIT=1)
C
      INTEGER I, I1, I2, IELE, IFED, IROW, NELF, NTERM
      DOUBLE PRECISION DMAT(3600), DSYMAT(1830)
      CHARACTER*80 FILNAM
C
C***  GET THE FILE NAME
C
      WRITE(6,100)
      READ(5,110)FILNAM
C
C***  OPEN THE FILE
C
      OPEN (IUNIT, FILE=FILNAM, STATUS='OLD', FORM='UNFORMATTED') C
C***  READ THE ELEMENT DATA
C
 10   READ(IUNIT,END=999) IELE, IFED, NELF
      WRITE(6,120) IELE, IFED, NELF
      NTERM = (NELF*(NELF+1))/2
      READ(IUNIT) (DSYMAT(I),I=1,NTERM)
      CALL EXPAND (DSYMAT, NELF, DMAT)
C
C***  WRITE MATRIX TO TERMINAL
C
      I2 = 0
      DO 20 IROW=1,NELF
	WRITE(6,130)IROW
	I1 = I2 + 1
	I2 = I2 + NELF
	WRITE(6,140)(DMAT(I),I=I1,I2)
 20   CONTINUE
      GO TO 10
C
 100  FORMAT(' ENTER NAME OF FILE')
 110  FORMAT(A80)
 120  FORMAT(/' ELEMENT =',I5,'  TYPE =',I4,'  NUMBER OF FREEDOMS ='I4)  130  FORMAT(/'ROW',I3)  140  FORMAT(1P6E13.5) C  999  CLOSE(IUNIT)
      END
C
      SUBROUTINE EXPAND (DMAT1, N, DMAT2)
C
C     EXPAND UPPER TRIANGULAR MATRIX TO FULL
C
      INTEGER I, J, K, N
      DOUBLE PRECISION DMAT1(*), DMAT2(N,N)
C
      K = 0
      DO 10 J=1,N
	DO 10 I=1,J
	  K = K + 1
	  DMAT2(I,J) = DMAT1(K)
	  DMAT2(J,I) = DMAT1(K)
 10   CONTINUE
      RETURN
      END




C version: 



/*    Sample progrm for reading the element matrices generated 

      in Model Solution
 */
#include <stdio.h> 

      void expand (double [], int, double[]); 

main() 

{
      int i, i1, i2, iBuf[5], iDum, iEle, iFed, iRet, iRow;
      int iNelf, iNread, iNterm, n;
      double dMat[3600], dSymat[1830];
      char cFilnam[80];
      FILE *cfPtr;
/*    Get the filename */ 

Prompt: 

      printf("Enter name of file\n"); 

      scanf("%s", cFilnam);
/*    Open the file */ 

      cfPtr = fopen(cFilnam, "r"); 

      if (cfPtr == NULL) goto Prompt;
/*    Read the element data */ 

NextElem: 

      iNread = fread (iBuf, sizeof(int), 5, cfPtr); 

      if (iNread ==5)
	 {
	  iEle	= iBuf[1];
	  iFed	= iBuf[2];
	  iNelf = iBuf[3];
	  printf("\nElement = %d  Type = %d Number of freedoms %d\n",
						      iEle, iFed, iNelf);
	  iNterm = (iNelf*(iNelf+1))/2;
	  iNread = fread (&iDum, sizeof(int), 1, cfPtr); 

	  iNread = fread (dSymat, sizeof(double), iNterm, cfPtr);
	  iNread = fread (&iDum, sizeof(int), 1, cfPtr);
	  expand (dSymat, iNelf, dMat);
/*	  Write the matrix */ 

	  i2 = -1; 

	  for (iRow=0;iRow<iNelf;iRow++)
	    {
	     printf("\nRow = %d\n",iRow);
	     i1 = i2 + 1;
	     i2 = i2 + iNelf;
	     n = 0;
	     for (i=i1;i<=i2;i++)
	       {
		printf("%13.5e",dMat[i]);
		n = n + 1;
		if (n==6)
		  {
		   printf("\n");
		   n = 0;
		  }
	       }
	     printf("\n");
	    }
	  goto NextElem; 

	 }
      iRet = fclose (cfPtr); 

} 

      void expand (double dMat1[], int iNrow, double dMat2[]) 

{
      int i, j, k, k1, k2;
      k = -1; 

      for (j=0;j<iNrow;j++)
	{
	 for (i=0;i<=j;i++)
	   {
	    k = k + 1;
	    k1 = i*iNrow + j;
	    k2 = j*iNrow + i;
	    dMat2[k1] = dMat1[k];
	    dMat2[k2] = dMat1[k];
	   }
	}
      return; 

}