DECLARE SUB Pager ()
REM one zone method for integration of
REM equations 14.24 to get r,v and P for a shell of gass in a
REM cepheid like variable
REM cgs units
PRINT CHR$(12);
PRINT "Adiabatic Radial Oscillation Model of a Cepheid"
G = 6.67259E-08
M = 1E+34
dt = 10000!
ms = 1E+29
gamma = 5! / 3!
GM = G * M
Pie = 4! * ATN(1!)
con = (4! * Pie) / ms

v0 = 0
tf = 1500000!
REM
DIM Press(200), radial(200), vel(200), time(200), Lumin(200)
Vi = 0!
Pi = 560000!
Ri = 1.7E+12
PRINT "Initial Conditions:"
PRINT "Velocity of shell = "; Vi; " cm/s"
PRINT "Radius of shell = "; Ri; " cm"
PRINT "Pressure in shell = "; Pi; " dynes/cm^2"
PRINT "Mass of shell = "; ms; "gm"
PRINT "Mass of star = "; M; "gm"
PRINT "Gamma of the gas equation pV^(gamma) ="; gamma
    CALL Pager

ncount = 0
FOR t = 0 TO tf STEP dt
ncount = ncount + 1
time(ncount) = t
Vf = Vi + ((con * Ri ^ 2 * Pi) - GM / Ri ^ 2) * dt
REM
Rf = Ri + Vf * dt
vel(ncount) = Vf
radial(ncount) = Rf
Pf = Pi * (Ri / Rf) ^ (5)
Press(ncount) = Pf
Lumin(ncount) = 4! * Rf ^ 2 * Pie
Pi = Pf
Vi = Vf
Ri = Rf
NEXT t
 
ip = 7
ix = 0
PRINT "time s      radial cm      Velocity cm/s  Press dyne/cm^2  Lum erg/s"
FOR i = 1 TO ncount
 IF ix = ip THEN
PRINT USING " ##.####^^^^^"; time(i); radial(i); vel(i); Press(i); Lumin(i)
 ix = 0
 ELSE
 ix = ix + 1
 END IF
NEXT i


CALL Pager
PRINT "Normalizing data"
REM normalize all data to one
REM
max = -1E+23
FOR i = 1 TO ncount
IF radial(i) > max THEN
max = radial(i)
ELSE
END IF
NEXT i
FOR i = 1 TO ncount
radial(i) = radial(i) / max
NEXT i
REM now do Vel
max = -1E+23
FOR i = 1 TO ncount
IF vel(i) > max THEN
max = vel(i)
ELSE
END IF
NEXT i
FOR i = 1 TO ncount
vel(i) = vel(i) / max
NEXT i
REM Now do pressure
max = -1E+23
FOR i = 1 TO ncount
IF Press(i) > max THEN
max = Press(i)
ELSE
END IF
NEXT i
FOR i = 1 TO ncount
Press(i) = Press(i) / max
NEXT i
REM Now do luminosity
max = -1E+23
FOR i = 1 TO ncount
IF Lumin(i) > max THEN
max = Lumin(i)
ELSE
END IF
NEXT i
FOR i = 1 TO ncount
Lumin(i) = Lumin(i) / max
NEXT i
    
OPEN "PLTTEK.DAT" FOR OUTPUT AS #2
PRINT #2, 1
PRINT #2, 4
PRINT #2, ncount
PRINT #2, "Normalized valuesm"
PRINT #2, "time in sec"
PRINT #2, "One-zone Cepheid Pulsation"
PRINT #2, "Radius, Velocity, Pressure, Luminosity"
FOR i = 1 TO ncount
PRINT #2, time(i), radial(i)
NEXT i
FOR i = 1 TO ncount
PRINT #2, time(i), vel(i)
NEXT i
FOR i = 1 TO ncount
PRINT #2, time(i), Press(i)
NEXT i
FOR i = 1 TO ncount
PRINT #2, time(i), Lumin(i)
NEXT i

CLOSE #2
CHAIN "Tek2wplt.bas"
END

SUB Pager
PRINT "Push RETURN to continue";
INPUT dum$
PRINT CHR$(12);
END SUB