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Fortran NAN error

  1. Apr 30, 2014 #1
    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:
    Code (Text):

        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
     
  2. jcsd
  3. Apr 30, 2014 #2

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    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?
     
  4. Apr 30, 2014 #3

    Borek

    User Avatar

    Staff: Mentor

    Do you know what NaN means?
     
  5. May 1, 2014 #4
    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:
    Code (Text):

    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:
    Code (Text):
            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    
     
     
  6. May 2, 2014 #5
    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
     
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