DECLARE SUB SUBGAIN ()
DECLARE SUB SUBDB ()
CLS
10
INPUT "Enter d to convert gain to db.  Enter g to convert db into gain. ", s$
   PRINT " "
   IF s$ = "g" THEN CALL SUBGAIN
   IF s$ = "d" THEN CALL SUBDB
   PRINT " "
   GOTO 10


SUB SUBDB

    PRINT "THIS CONVERTS GAIN INTO DECIBELS"
    INPUT "Enter p if you are using power gain ( 10 * LOG (gain) ): "; p$
200 INPUT "Enter the gain: "; g
    IF g < 0 THEN
       PRINT "negative not defined"
       GOTO 200
    END IF
    IF g < 1D-41 THEN
      PRINT "gain too small to calculate.  Zero gain is negative infinity db."
      PRINT "   note: (gain a) * (gain b) converts to (gain a in db) + (gain b in db)"
      GOTO 200
    END IF

    IF g > 1D+36 THEN
       PRINT "gain too large to calculate"
       PRINT "   note: (gain a) * (gain b) converts to (gain a in db) + (gain b in db)"
       GOTO 200
       END IF

    a = 20
    IF p$ = "p" THEN a = 10

    DB = a * (LOG(g) / LOG(10))



REM here LOG is natural log (base e).  To convert to base 10, divide by natural log of 10.
   
    PRINT DB, " decibels"

END SUB

SUB SUBGAIN
PRINT "THIS CONVERTS DECIBELS INTO GAIN."
    INPUT "Enter p if you are using power gain ( 10 * LOG (gain) ): "; p$
    INPUT "Enter the number of decibels. ", d

  
  
  
  
  
    a = 20
    IF p$ = "p" THEN a = 10
    GAIN = EXP((d / a) * LOG(10))
REM gain = 10^(d/a)  would also work but I wanted to use natural log as an exercise


    PRINT "GAIN = "; GAIN



END SUB