线性代数方程组的解法-追赶法
procedure TRIDAG(A, B, C, R:array of real;var U:array of real; N:integer);
var
GAM:array[0..100] of real;
J:integer; BET:real;
begin
If B[1] = 0 Then Exit;
BET:=B[1];
U[1]:=R[1] / BET;
For J:=2 To N do
begin
GAM[J]:=C[J - 1] / BET;
BET:=B[J] - A[J] * GAM[J];
If BET = 0 Then Exit;
U[J]:=(R[J] - A[J] * U[J - 1]) / BET;
end;
For J:=N - 1 DownTo 1 do
U[J]:=U[J] - GAM[J + 1] * U[J + 1];
end;