REM
REM THIS IS PROGRAM HOLECALC.BAS. IT CALCULATES THE PROPERTIES OF
REM A NEWTONIAN BLACK HOLE (MASS DENSITY OR RADIUS) GIVEN ONE OF 
REM THOSE PROPERTIES.***THIS IS VERSION # 2***
REM IT CAN BE SHOWN THAT IF K = 3*C^2/(4*Pi*G) = 3.22 * TEN(27) GM/CC
REM THAT R^2*D = K, WHERE C IS THE VELOCITY OF LIGHT, G IS
REM NEWTON'S GRAVITATIONAL CONSTANT, PI = 3.1415926, R IS THE
REM IS THE CRITICAL RADIUS AND D IS THE CRITICAL DENSITY AT THAT
REM RADIUS.
REM PREVIOUS ESTIMATES WERE BASED ON A MISTAKE BY THE REV MR
REM MICHELL IN PROCEDINGS OF ROYAL ACADEMY (LONDON), WHO ASSUMED
REM THAT IF THE ESCAPE VELOCITY WAS C, BODIES WOULD BE UNABLE TO
REM LEAVE THE BLACK HOLE. IT IS PATENTLY OBVIOUS FROM CELESTIAL 
REM MECHANICS THAT SUBLUMINIAL VELOCITY OBJECTS WOULD BE ABLE TO 
REM ORBIT UNTIL THE ESCAPE VELOCITY REACHED 2^.5 * C, AT WHICH
REM NOT EVEN LIGHT WOULD BE ABLE TO ORBIT.
REM THIS PROGRAM WAS WRITTEN BY MIKE FINERTY, 11/25/84 IN S-BASIC
REM 200 YEARS AFTER MR MICHELL'S MISTAKE. REVISED 4/23/85.
REM *************************************************************
REM
10 VAR K,G,RLOG,DLOG,MLOG,QUANT,SOLS,L = REAL
VAR ANS, RESPONSE = STRING:10 
    LET L = 2.302585
    LET K = 3.22E+27
REM
     PRINT "PROGRAM RETURNS CRITICAL VALUE OF R,D&M IN CGS SYSTEM"
     PRINT "PLEASE SELECT INPUT"
     PRINT
     PRINT "R ....... RADIUS IN CM"
     PRINT 
     PRINT "D ....... DENISTY IN GRAMS/CC"
     PRINT
     PRINT "M ....... MASS IN GRAMS"
     PRINT
     PRINT "MLOG .... LOGARITHM OF MASS IN GRAMS"
     PRINT
REM
    INPUT "PLEASE INPUT LETTER OF CHOICE"; RESPONSE
    INPUT "PLEASE INPUT QUANTITY OF CHOICE"; QUANT
    IF ABS(LOG(QUANT)/L) > 34 THEN PRINT "OUT OF RANGE"
    IF ABS(LOG(QUANT)/L) > 34 THEN GOTO 20
    PRINT RESPONSE;" = ";QUANT  
REM
     CASE RESPONSE OF
"R": BEGIN
     DLOG =  LOG(K)/L - (2*LOG(QUANT)/L))
     MLOG = .6220886 + LOG(K)/L + LOG(QUANT)/L
     PRINT "DENSITY=";10^(DLOG-INT(DLOG));"TEN";INT(DLOG);" GMS/CC"
     PRINT "MASS = ";10^(MLOG-INT(MLOG));"TEN";INT(MLOG);" GMS"
     SOLS = MLOG - 33.29885     
     PRINT "SOLAR MASSES = ";10^(SOLS-INT(SOLS));"TEN";INT(SOLS);" SOLS"
     END
"D": BEGIN
     RLOG =  0.5*(LOG(K)/L - LOG(QUANT)/L)    
     MLOG = .6220886  + 0.5*(3*LOG(K)/L-LOG(QUANT)/L)
     SOLS = MLOG - 33.29885
     PRINT "RADIUS =";10^(RLOG-INT(RLOG));"TEN";INT(RLOG);" CM"
     PRINT "MASS =";10^(MLOG-INT(MLOG));"TEN";INT(MLOG);" GMS"
     PRINT "SOLAR MASSES = ";10^(SOLS-INT(SOLS));"TEN";INT(SOLS);" SOLS"
     END
"M": BEGIN
     DLOG = 1.244177 + 3*LOG(K)/L -2*LOG(QUANT)/L
     RLOG = -.6220886 +LOG(QUANT)/L-LOG(K)/L
     SOLS = LOG(QUANT)/L - 33.29885
     PRINT "DENSITY = ";10^(DLOG-INT(DLOG));"TEN";INT(DLOG);" GMS/CC"
     PRINT "RADUIS = ";10^(RLOG-INT(RLOG));"TEN";INT(RLOG);" CM"
     PRINT "SOLAR MASSES = ";10^(SOLS-INT(SOLS));"TEN";INT(SOLS);" SOLS"
     END
"MLOG": BEGIN
        SOLS = QUANT - 33.2989
        DLOG = 1.24418 + 3*LOG(K)/L - 2*QUANT
        RLOG = -.622089 + QUANT - LOG(K)/L
        PRINT "SOLAR MASSES =";10^(SOLS-INT(SOLS));"TEN";INT(SOLS);" SOLS"
        PRINT "DENSITY =";10^(DLOG-INT(DLOG));"TEN";INT(DLOG);" GMS/CC"
        PRINT "RADIUS =";10^(RLOG-INT(RLOG));"TEN";INT(RLOG);" CM"
        END    
END
20 PRINT "DO YOU WISH TO TRY ANOTHER VARIABLE OR VALUE? Y/N?"
INPUT ANS
IF ANS = "Y" OR ANS = "y" THEN GOTO 10