DECLARE FUNCTION f! (A!, V!, M!, k!, t!)
10 PRINT CHR$(12);
20 PRINT "MAXWELL'S SPEED DISTRIBUTION FUNCTION"
30 PRINT "f(v)=A*v*v*EXP(-M*v*v/(2.*k*T))  "
REM
REM GE Copeland
REM dept of Physics
REM Old Dominion University
REM Norfolk VA
REM 3/2001
REM


600 DIM Vel(500), n(500)
800 pi = 4! * ATN(1!)
900 M = 9.109558E-31
u = 1.6605402D-27


PRINT "Select the mass of the species"
PRINT "1. Hydrogen atom"
PRINT "2. Helium atom"
PRINT "3. Oxygen Atom"
PRINT "4. An electron"
PRINT "5. You input a mass - in Kg"
PRINT "Input 1,2,3,4, or 5";
INPUT askm

IF askm = 1 OR askm = 2 OR askm = 3 OR askm = 4 OR askm = 5 THEN
GOTO 911
ELSE
GOTO 900
END IF
911 REM
IF askm = 1 THEN M = 1.008 * u
IF askm = 2 THEN M = 4.003 * u
IF askm = 3 THEN M = 15.999 * u
IF askm = 4 THEN M = 9.10393897D-31
IF askm = 5 THEN
PRINT "Input the atomic mass of the species";
INPUT M
M = M * u
END IF

1000 k = 1.380622E-23
1100 C = 299792500#
1103 PRINT " THE MASS OF THE PARTICLE IS "; M; " KG"
1107 PRINT "THE TEMPERATURE WILL BE varied from 300 to 10000 IN STEPS OF 500K"

1200 H = 0
     PRINT "Temp(K)          V mp         V avg        V rms       all m/s"
1300 FOR t = 300 TO 10000 STEP 500
1400
1500   V1 = SQR(2! * k * t / M)
       vmp = SQR(2! * k * t / M)
       vavg = SQR(8! * k * t / (pi * M))
       Vrms = SQR(3 * k * t / M)
      PRINT t, vmp, vavg, Vrms
      tsave = t
     NEXT t
    PRINT "Do you want to input a Temperature for a distribution plot? <Yes or No>"
    INPUT Task$
    IF LEFT$(Task$, 1) = "N" OR LEFT$(Task$, 1) = "n" THEN
    PRINT " Will use the Last temperature "; tsave
    ELSE
    PRINT "Input the Temperature";
    INPUT tsave
    Vrms = SQR(3 * k * tsave / M)
    END IF
1900 FOR X = 1 TO 299
    A = 4! * pi * (M / (2 * pi * k * tsave)) ^ (3 / 2)
2000 H = H + 1
2100 V = X * Vrms / 100!
2200 E = .5 * M * V * V
2300 n(H) = f(A, V, M, k, tsave)
2500 Vel(H) = V

2700  NEXT X

2800 REM
    
3000 OPEN "PLTTEK.DAT" FOR OUTPUT AS #2
3100 PRINT "OUTPUT WILL BE TO PLTTEK DATA FOR TEKTRONIX PLOTTING"
3200 PRINT #2, 1
3300 PRINT #2, 1
3400 PRINT #2, INT(H)
3500 PRINT #2, "PROBABILITY"
3600 PRINT #2, "VELOCITY (M/S)"
3700 PRINT #2, "MAXWELL's Speed Distribution"
3800 PRINT #2, "Temperature ="; tsave; " K species ="; M / u; " AMU"
3900 FOR J = 1 TO H
4000 PRINT #2, Vel(J), n(J)
4100 NEXT J
CLOSE #2
CHAIN "Tek2wplt.bas"

4200 END

 FUNCTION f (A, V, M, k, t)
f = A * V * V * EXP(-M * V * V / (2! * k * t))
END FUNCTION