invert.for

本程序是D.R.J.OWEN主编的FINITE ELEMENTS IN PLASTICITYG一书中第八章例题的有限元程序

C$DEBUG
C$LARGE
	SUBROUTINE INVERT(AMATX,BMATX,NARAY) !(Page 288)
C*********************************************************************
C
C*** TO PROVIDE THE INVERSE OF AMATX AS BMATX
C
C*********************************************************************
	DIMENSION AMATX(4,4),BMATX(4,4)
      DO 10 IARAY=1,NARAY
	DO 10 JARAY=1,NARAY
	BMATX(IARAY,JARAY)=0.0
   10 IF(IARAY.EQ.JARAY) BMATX(IARAY,JARAY)=1.0
      DO 20 IARAY=1,NARAY
	DENOM=AMATX(IARAY,JARAY)
	DO 30 JARAY=1,NARAY
	AMATX(IARAY,JARAY)=AMATX(IARAY,JARAY)/DENOM
   30	BMATX(IARAY,JARAY)=BMATX(IARAY,JARAY)/DENOM
      KARAY=IARAY+1
	IF(KARAY.GT.NARAY) GO TO 40
	DO 20 JARAY=1,NARAY
	CONST=AMATX(JARAY,IARAY)
	DO 20 LARAY=IARAY,NARAY
	AMATX(JARAY,LARAY)=AMATX(JARAY,LARAY)-AMATX(IARAY,LARAY)
     . *CONST
   20 BMATX(JARAY,LARAY)=BMATX(JARAY,LARAY)-BMATX(IARAY,LARAY)
     . *CONST
   40 CONTINUE
      DO 50 IARAY=1,NARAY
	KARAY=NARAY-IARAY+2
	LIMIT=KARAY-1
	DO 50 LARAY=1,NARAY
	CONST=AMATX(LARAY,KARAY)
	DO 50 JARAY=1,NARAY
	AMATX(LARAY,JARAY)=AMATX(LARAY,JARAY)-AMATX(KARAY,JARAY)
     . *CONST
   50 BMATX(LARAY,JARAY)=BMATX(LARAY,JARAY)-BMATX(KARAY,JARAY)
     . *CONST
	RETURN
	END