Why am I getting a NaN Error when Running my Fortran Program?

[shipman]

Hi to everyone,

I am quite new to forum and fortran. Basically, i am trying to calculate the bubble radius using RP model and this is my code:

	IMPLICIT DOUBLE PRECISION (A-H,O-Z)
	IMPLICIT INTEGER (I-N)
C	! Declare local constant Pi
	REAL, PARAMETER :: Pi = 3.1415927D0	

C	*************************************************************
C	*    OUTPUT VARIABLES                                        *
C	*************************************************************
	OPEN (10,FILE='DT12.csv',STATUS='UNKNOWN')

C	************INPUT   VARIABLES**************
      DT=1.0D-12	!time step
	TEND=8.0D-4 ! ENDTIME
      DIN= 8.0D-4    !Initial BUBle Dia ometer  
      
C	********   SOME   VARIABLE DATA*****************
      ROL  =1.0D3  ! DENSITY   [LIQUID] kg/m-3
      DMYUL=1.002D-3 ! VISCOSITY [LIQUID]
     	PV=2.3D3    ! SATURATION PRESSURE 
	SIGMA=7.277D-2 ! SURFACE TENSION 
	BETA=1.4D0    ! pressure parameter
	VO=4.78D-9 !constant bubble volume 
	PO=1.00072D5 !used in pres. calculation 
      
	RO=0.5D0*DIN   ! BUBBLE RADIUS AT OLD TIME STEP
	R =0.5D0*DIN !0.5D0*1.07D-3  ! CURRENT BUBBLE RADIUS

	! Initial bubble volume

	VB= 4.0D0*Pi*(RO**3.0D0)/3.0D0 
	
	PG = PO*(VB/VO)**BETA ! PRESSURE OF NON-CONDENSING GAS

	PBUB  =PG +PV !bubble pressure
	
	PSUR=1.01325D5 !enviroment pressure=constant 

	TP    =0.0D0
	N     =0

C	************OUT PUT  INFOMATION*******************************

      NDATA=INT(TEND/DT)
      WRITE(*,100) DIN*1.0D3
      WRITE(*,300) NDATA

C	**************************************************************
C	 ***************LOOP 1  START*********************************
C	**************************************************************
10    TP=TP+DT

      N=N+1
	


	! Solving RP equation

      RR=(PBUB-PSUR
     &    -4.0D0*DMYUL/DT*(R-RO)/R
     &    -2.0D0*SIGMA/R)/ROL
      RNE=2.0D0*R-RO-1.5D0*(R-RO)**2.0D0/R+DT*DT*RR/R
	    
		
	 ! BUBBLE RADIUS AT NEW TIME STEP
      
	IF(RNE*2.0D0.LE.0)   RNE= 0.5d0*DIN
	IF(RNE*2.0D0.GE.2.0d-3)   RNE= 2.0d-3
      
	
	VB= 4.0D0*Pi*(RNE**3.0D0)/3.0D0 
	
	PG = PO*(VB/VO)**BETA ! PRESSURE OF NON-CONDENSING GAS

	PBUB  =PG+PV !bubble pressure

      DRDT=(RNE-R)/DT


	RO =R
	R  =RNE
	RNE=0.0D0

     
C	 *************************************************************
C	*						 OUTPUT                              *
C	*********************WRITE( *,400)*****************************************
     
      
	IF (MOD(N,NDATA/10000).EQ.1) THEN  !screen display data
       WRITE( *,400) N,TP,((3.0D0*VB)/(4.0d0*Pi))**(1.0d0/3.0D0)*1.0D3,
     & PG/1.0d6,DRDT
	end if
	
	if (MOD(N,NDATA/10000).EQ.1) THEN  !csv.data
	  WRITE( *,400) N,TP,((3.0D0*VB)/(4.0d0*Pi))**(1.0d0/3.0D0)*1.0D3,
     & PG/1.0d6,DRDT
      END IF
     
     	IF (TP.LT.TEND) GOTO 10  !time iteration

	
	goto 101
	
	
C *************************************************************
C *    LOOP END                                               *
C *************************************************************
C
101   write(*,*)RNE
  
  100 FORMAT('INITIAL DIAMETER(um)='F6.2)
  200 FORMAT('LIQUID PRESSURE(kPa)='F6.2)
  300 FORMAT('CYCLE NUMBER='8X,I16)
  400 FORMAT(I13,4(1X,1H,E13.6))
 
	CLOSE(10)

	
	
	STOP
	END

could someone tell me that why i get NaN error when i run the program?

Best Regards

 

[SteamKing]

Could you provide some more detail about how the program informs you that the NaN error has occurred?

What is the exact wording of the NaN error message?

 

[Borek]

Do you know what NaN means?

 

[gsal]

took the source
saved the file as *.f90
replaced all "C" in first column for "!"
removed continuation marks "&" and simply glued lines back together...there is room
increased time step from e-12 to e-8, for good measure
compiled program
run it

First few lines:

INITIAL DIAMETER(um)=  0.80
CYCLE NUMBER=                   79999
            1 , 0.100000E-07 , 0.400000E+00 , 0.177292E-02 ,-0.291038E-02
            1 , 0.100000E-07 , 0.400000E+00 , 0.177292E-02 ,-0.291038E-02
            8 , 0.800000E-07 , 0.399999E+00 , 0.177290E-02 ,-0.232831E-01
            8 , 0.800000E-07 , 0.399999E+00 , 0.177290E-02 ,-0.232831E-01
           15 , 0.150000E-06 , 0.399996E+00 , 0.177286E-02 ,-0.436557E-01
           15 , 0.150000E-06 , 0.399996E+00 , 0.177286E-02 ,-0.436557E-01
           22 , 0.220000E-06 , 0.399993E+00 , 0.177278E-02 ,-0.640284E-01
           22 , 0.220000E-06 , 0.399993E+00 , 0.177278E-02 ,-0.640284E-01

Last few lines:

        79927 , 0.799872E-03 , 0.200000E+01 , 0.152885E+01 , 0.000000E+00
        79927 , 0.799872E-03 , 0.200000E+01 , 0.152885E+01 , 0.000000E+00
        79934 , 0.799942E-03 , 0.200000E+01 , 0.152885E+01 , 0.000000E+00
        79934 , 0.799942E-03 , 0.200000E+01 , 0.152885E+01 , 0.000000E+00
   0.00000000

 

[shipman]

Thank you so much for your all kind replies. Yeah "gsal" finally i could run the program correctly. I found that NaN shows mathematical error which can be derived from dividing by zero...Thank you