Sub LUDCMP(A(), N, INDX(), D)
NMAX = 100
TINY = 1E-20
Dim VV(100)
D = 1#
For I = 1 To N
AAMAX = 0#
For J = 1 To N
If Abs(A(I, J)) > AAMAX Then AAMAX = Abs(A(I, J))
Next J
If AAMAX = 0# Then Print "Singular matrix."
VV(I) = 1# / AAMAX
Next I
For J = 1 To N
If J > 1 Then
For I = 1 To J - 1
Sum = A(I, J)
If I > 1 Then
For K = 1 To I - 1
Sum = Sum - A(I, K) * A(K, J)
Next K
A(I, J) = Sum
End If
Next I
End If
AAMAX = 0#
For I = J To N
Sum = A(I, J)
If J > 1 Then
For K = 1 To J - 1
Sum = Sum - A(I, K) * A(K, J)
Next K
A(I, J) = Sum
End If
DUM = VV(I) * Abs(Sum)
If DUM >= AAMAX Then
IMAX = I
AAMAX = DUM
End If
Next I
If J <> IMAX Then
For K = 1 To N
DUM = A(IMAX, K)
A(IMAX, K) = A(J, K)
A(J, K) = DUM
Next K
D = -D
VV(IMAX) = VV(J)
End If
INDX(J) = IMAX
If J <> N Then
If A(J, J) = 0# Then A(J, J) = TINY
DUM = 1# / A(J, J)
For I = J + 1 To N
A(I, J) = A(I, J) * DUM
Next I
End If
Next J
If A(N, N) = 0# Then A(N, N) = TINY
End Sub
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