bwBASIC/BP100/BAYES.OUT

         BAYES PROBABILITIES

THIS THEOREM USES BAYES THEOREM TO REVISE ESTIMATES OF
THE PROBABILITIES OF THE OCCURRENCE OF THE VARIOUS STATES OF
NATURE. INPUT TO THIS PROGRAM ARE THE PROBABILITIES OF A
A FINITE AND USER SELECTABLE NUMBER OF STATES OF NATURE,
THESE PROBABILITIES MUST SUM UP TO 1. IN ADDITION,
THERE MUST BE INPUT FOR EACH STATE OF NATURE THE PROBABILITY
OF A CERTAIN EVENT,SAY B, OCCURRING GIVEN THAT STATE OF
IS THE TRUE STATE OF NATURE. THEN THE PROGRAM WILL COMPUTE
THE CONDITIONAL PROBAILITIES OF EACH OF THE STATES OF NATURE
BEING TRUE GIVEN THAT EVENT B OCCURS. THESE ARE CALLED
POSTERIOR PROBABILITIES AND MAY BE USED IN DECISION MAKING

PRESS ENTER TO BEGIN? 
ENTER PROBABILITIES OF POSSIBLE STATES OF NATURE 1 BY 1.
THESE PROBABILITIES SHOULD ADD TO 1.

ENTER PROB. ST. OF NATURE 1 (-1 TO END)? 12
ENTER PROB. ST. OF NATURE 2 (-1 TO END)? 34
ENTER PROB. ST. OF NATURE 3 (-1 TO END)? 56
ENTER PROB. ST. OF NATURE 4 (-1 TO END)? -1
PROBABILITIES SUM TO 102 THIS SHOULD BE STANDARDIZED
TO SUM TO 1. ENTER 1 TO STANDARDIZE, 0 TO END? 1
ENTER COND.PROB. OF EVENT B GIVEN ST.OF.NATURE 1 ? .145
ENTER COND.PROB. OF EVENT B GIVEN ST.OF.NATURE 2 ? .267
ENTER COND.PROB. OF EVENT B GIVEN ST.OF.NATURE 3 ? .389
IS LINE PRINTER OUTPUT DESIRED(Y/N)? Y
S OF N    ORIG.      PROB B       POSTERIOR PROB
          PROB.   GIVEN S OF N    S OF N GIVEN B
   1      0.118      0.145            0.053
   2      0.333      0.267            0.278
   3      0.549      0.389            0.668
PRESS ENTER FOR ANOTHER COMPUTATION? 0