d5r4.txt

来自「常用的数值算法的VB程序」· 文本 代码 · 共 41 行

Private Sub Command1_Click()
     'PROGRAM D5R4
     'Driver for routine CHEBFT
     NVAL = 40
     PIO2 = 1.5707963
     EPS = 0.000001
     Dim C(40)
     A = -PIO2
     B = PIO2
     Call CHEBFT(A, B, C(), NVAL)
    'Test result
     Print
     Print Tab(5); "How many terms in Chebyshev evaluation?"
     'Input MVAL , between 1 and 40, MVAL=0 TO END
     MVAL = 20
     Print Tab(5); MVAL
     If (MVAL <= 0) Or (MVAL > NVAL) Then Exit Sub
     Print Tab(5); "   X          Actual       Chebyshev fit"
     For I = -8 To 8 Step 1
         X = I * PIO2 / 10#
         Y = (X - 0.5 * (B + A)) / (0.5 * (B - A))
     'Evaluate Chebyshev polynomial without using
     'routine CHEBEV
         T0 = 1#
         T1 = Y
         F = C(2) * T1 + C(1) * 0.5
         For J = 3 To MVAL
             DUM = T1
             T1 = 2# * Y * T1 - T0
             T0 = DUM
             TERM = C(J) * T1
             F = F + TERM
         Next J
         Print Tab(4); Format$(X, ".##0000");
         Print Tab(19); Format$(FUNC(X), "#.###000");
         Print Tab(33); Format$(F, "#.###000")
     Next I
End Sub
Function FUNC(X)
    FUNC = (X ^ 2) * (X ^ 2 - 2#) * Sin(X)
End Function