REM this is Program CRAMERS3.BAS, A program to calculate the
REM solutions to 3 simultaneous linear equations in 3 unknowns 
REM using Cramer's Rule of substitution to form 3X3 Determinates
REM
REM THIS PROGRAM WAS WRITEN BY MICHAEL P. FINERTY 10/18/84
REM ************************************************************
10  REM 
REM A(N)*X1 + B(N)*X2 + C(N)*X3 = D IS AN EQUATION IN 3 UNKNOWNS
VAR DET, DET0, DET1, DET2, DET3  = REAL.DOUBLE
VAR A$ = STRING
VAR N = INTEGER
REM
DIM COM REAL.DOUBLE   A(3) B(3) C(3) D(3) X(3) Y(3) Z(3)
REM
REM READ IN VALUES OF A,B,C&D FOR EACH OF THE EQUATIONS
REM
FOR N = 1 TO 3
    PRINT "PLEASE INPUT A(";N;")"
    INPUT A(N)
    PRINT "PLEASE INPUT B(";N;")"
    INPUT B(N)
    PRINT "PLEASE INPUT C(";N;")"
    INPUT C(N)
    PRINT "PLEASE INPUT D(";N;")"
    INPUT D(N)
NEXT N
    FOR N = 1 TO 3
        X(N) = A(N)
        Y(N) = B(N) 
        Z(N) = C(N)
    NEXT N
REM
GOSUB 100
REM
   DET0 = DET
IF DET0 = 0 THEN PRINT "INCONSISTANT EQUATIONS, NO SOLUTION"
IF DET0 = 0 THEN 200
   FOR N = 1 TO 3
      X(N) = D(N)
      Y(N) = B(N)
      Z(N) = C(N)
   NEXT N
REM
GOSUB 100
REM
     DET1 = DET
PRINT "X1 = "; DET1/DET0
REM
    FOR N = 1 TO 3
       X(N) = A(N)
       Y(N) = D(N)
       Z(N) = C(N)
    NEXT N
REM     
GOSUB 100
REM
    DET2 = DET
PRINT "X2 =";DET2/DET0
REM
     FOR N = 1 TO 3
       X(N) = A(N)
       Y(N) = B(N)
       Z(N) = D(N)
    NEXT N
REM
GOSUB 100
REM
     DET3 = DET
REM
PRINT "X3 = ";DET3/DET0
REM
200 REM
PRINT "DO YOU WISH TO SOLVE ANOTHER SET OF EQUATIONS? Y/N?"
INPUT A$ 
IF A$ = "y" OR A$ = "Y" THEN 10
END
100 REM SUBROUTINE TO CALCULATE DETERMINATES FROM X(N),Y(N) AND
REM Z(N)
REM
    DET = X(1)*Y(2)*Z(3) + X(2)*Y(3)*Z(1) + X(3)*Y(1)*Z(2)
    DET = DET - X(3)*Y(2)*Z(1) - X(1)*Y(3)*Z(2) - X(2)*Y(1)*Z(3)
RETURN