Вычисления матрицы 4-го порядка, обратной заданной

RANDOMIZE TIMER
n = 4
DIM a(n, n), b(n, n)
FOR i = 1 TO n
    FOR j = 1 TO n
        a(i, j) = INT(RND * 11)
    NEXT
NEXT
FOR i = 1 TO n
    FOR j = 1 TO n
        PRINT a(i, j);
    NEXT
    PRINT
NEXT
FOR j = 1 TO n
    det = det + a(1, j) * aij(a(), n, 1, j)
NEXT
PRINT det
IF det = 0 THEN PRINT "the inverse matrix does not exist": END
FOR i = 1 TO n
    FOR j = 1 TO n
        b(i, j) = aij(a(), n, j, i) * 1 / det
    NEXT
NEXT
PRINT STRING$(80, 196)
FOR i = 1 TO n
    FOR j = 1 TO n
        PRINT b(i, j);
    NEXT
    PRINT
NEXT
 
FUNCTION aij (a(), n, ki, kj)
DIM t(n - 1, n - 1)
FOR i = 1 TO n
    IF i <> ki THEN
        fj = 0
        FOR j = 1 TO n
            IF j <> kj THEN
                t(i - fi, j - fj) = a(i, j)
            ELSE
                fj = 1
            END IF
        NEXT
    ELSE
        fi = 1
    END IF
NEXT
res = t(1, 1) * t(2, 2) * t(3, 3)
res = res + t(3, 1) * t(1, 2) * t(2, 3)
res = res + t(1, 3) * t(2, 1) * t(3, 2)
res = res - t(1, 3) * t(2, 2) * t(3, 1)
res = res - t(1, 1) * t(3, 2) * t(2, 3)
res = res - t(3, 3) * t(2, 1) * t(1, 2)
res = (-1) ^ (ki + kj) * res
aij = res
END FUNCTION

RANDOMIZE TIMER
DO
    INPUT "enter n(n>0): ", n
LOOP UNTIL n > 0
DIM a(n, n), e(n, n)
FOR i = 1 TO n
    FOR j = 1 TO n
        a(i, j) = INT(RND * 11)
    NEXT
NEXT
FOR i = 1 TO n
    e(i, i) = 1
NEXT
FOR i = 1 TO n
    FOR j = 1 TO n
        PRINT a(i, j);
    NEXT
    PRINT
NEXT
PRINT STRING$(80, 196)
FOR k = 1 TO n
    t = a(k, k)
    IF t = 0 THEN t = swapi(a(), e(), n, k)
    IF t = 0 THEN PRINT "the inverse matrix does not exist": END
    FOR j = 1 TO n
        a(k, j) = a(k, j) / t
        e(k, j) = e(k, j) / t
    NEXT
    FOR i = k + 1 TO n
        t = a(i, k)
        FOR j = 1 TO n
            a(i, j) = a(i, j) - a(k, j) * t
            e(i, j) = e(i, j) - e(k, j) * t
        NEXT
    NEXT
NEXT
FOR k = n TO 1 STEP -1
    FOR i = k - 1 TO 1 STEP -1
        t = a(i, k)
        FOR j = 1 TO n
            a(i, j) = a(i, j) - a(k, j) * t
            e(i, j) = e(i, j) - e(k, j) * t
        NEXT
    NEXT
NEXT
FOR i = 1 TO n
    FOR j = 1 TO n
        PRINT e(i, j);
    NEXT
    PRINT
NEXT
 
FUNCTION swapi (a(), e(), n, k)
FOR i = k + 1 TO n
    IF a(i, k) <> 0 THEN q = i: EXIT FOR
NEXT
FOR i = k TO n
    SWAP a(q, i), a(k, i)
    SWAP e(q, i), e(k, i)
NEXT
swapi = a(k, k)
END FUNCTION

n = 4
DIM a(n, n), b(n)
FOR i = 1 TO n
    FOR j = 1 TO n
        a(i, j) = INT(RND * 11)
        PRINT a(i, j);
    NEXT
    PRINT
NEXT
PRINT det(a(), b(), n, 1)
FUNCTION det (a(), b(), n, k)
IF k = n THEN
    FOR i = 1 TO n
        IF b(i) = 0 THEN res = a(k, i): EXIT FOR
    NEXT
ELSE
    res = 0
    q = 1
    FOR i = 1 TO n
        IF b(i) = 0 THEN
            q = q + 1
            b(i) = 1
            res = res + (-1) ^ (q) * a(k, i) * det(a(), b(), n, k + 1)
            b(i) = 0
        END IF
    NEXT
END IF
det = res
END FUNCTION