第十五章  VB NET電算機及2D函數圖繪製

程式設計

15.1 前言

VB NET電算機程式設計及2D函數圖繪製程式設計與運算法則(Algorithm) ，其與VB 6.0，除所用語法稍有不同外，兩者多非常相似。因此我們可以將原VB 6電算機程式設計升級至VB Net，後修改部份語法即可。VB Net指令按鈕控制項因沒有群組的索引屬性(Index)，因此有群組索引屬性按鈕之相關程序須另行設計，原引用之自訂數學函數，可改用VB Net內建函數。

下面我們將介紹

15.2指令按鈕及功能鍵介紹

為方便介紹，特將電算機之功能鍵及按鈕標題，依出現先後位置抄錄如下。

下表為對照於上表之指令按鈕名稱。

下表為三角函數及反三角函數等資料輸入及輸出類型說明

如需使用到函數繪圖功能，則點按開啟圖框功能鍵，就能開啟及使用到函數繪圖功能，開啟圖框後整個畫面如下圖所示。

(1)原函數指令程式cmdfunc_Click(Index As Integer)，如不使用自訂動態群組指令控制項情況下,須分別列出共同事件如下：

Private Sub cmdfunc_0_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdfunc_0.Click, _

          cmdfunc_1.Click, cmdfunc_2.Click, cmdfunc_3.Click, cmdfunc_4.Click, cmdfunc_5.Click, cmdfunc_6.Click, _

          cmdfunc_7.Click, cmdfunc_8.Click, cmdfunc_9.Click, cmdfunc_10.Click, cmdfunc_11.Click, cmdfunc_18.Click, _

        cmdfunc_19.Click, cmdfunc_20.Click, cmdfunc_21.Click, cmdfunc_22.Click, cmdfunc_23.Click, cmdfunc_24.Click, _

        cmdfunc_25.Click, cmdfunc_26.Click, cmdfunc_27.Click, cmdfunc_28.Click, cmdfunc_29.Click, cmdfunc_30.Click, _

        cmdfunc_31.Click, cmdfunc_32.Click, cmdfunc_33.Click, cmdfunc_34.Click, cmdfunc_35.Click, cmdfunc_36.Click, _

        cmdfunc_37.Click, cmdfunc_38.Click, cmdfunc_39.Click, cmdfunc_40.Click, cmdfunc_41.Click, cmdfunc_42.Click, _

        cmdfunc_43.Click, cmdfunc_44.Click, cmdfunc_45.Click, cmdfunc_46.Click, cmdfunc_47.Click, cmdfunc_48.Click, _

        cmdfunc_49.Click, cmdfunc_50.Click, cmdfunc_51.Click, cmdfunc_52.Click, cmdfunc_53.Click, cmdfunc_54.Click, _

        cmdfunc_55.Click, cmdfunc_56.Click, cmdfunc_57.Click, cmdfunc_58.Click, cmdfunc_59.Click

        glcmdfunc = LCase(DirectCast((sender), Button).Name.ToString)

        Dim buttext As String = DirectCast((sender), Button).Text.ToString

        txtShow.Text = txtShow.Text + buttext + "("

    End Sub

上述中glcmdfunc為指令按鈕(扣除12~17按鈕以外)為區分指令按鈕標題名稱的公有變數，供其他程序呼叫。Buttext則為指令按鈕標題名稱作為函數名稱使用。

按鈕12~17部份則另設計如下：

    Private Sub cmdfunc_12_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdfunc_12.Click, _

                 cmdfunc_13.Click, cmdfunc_14.Click, cmdfunc_15.Click, cmdfunc_16.Click, cmdfunc_17.Click

        glcmdfunc = LCase(DirectCast((sender), Button).Name.ToString)

        Dim buttext As String = DirectCast((sender), Button).Text.ToString

        txtShow.Text = txtShow.Text + buttext + "("""

    End Sub

等號指令按鈕cmdequal_Click()，則配合設計為：

Private Sub cmdequal_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Cmdequal.Click

        Dim stArray() As String, Xtpt As Double, Ytpt As Double

        Dim StTpt As String

        On Error Resume Next

        Dim expression As String

        Dim com As Control

        StTpt = Trim$(txtShow.Text)

        stArray = Split(StTpt, "(", -1, vbTextCompare)

        Select Case glcmdfunc

            Case "cmdfunc_42", "cmdfunc_43"

                stArray = Split(stArray(1), ",", -1, vbTextCompare)

                Ytpt = Val(stArray(0))

                Xtpt = Mid(stArray(1), 1, Len(stArray(1)) - 1)

                If glcmdfunc = "cmdfunc_42" Then txtInput.Text = Atn2(Ytpt, Xtpt)

                If glcmdfunc = "cmdfunc_43" Then txtInput.Text = Atn2D(Ytpt, Xtpt)

                GoTo 60

            Case "cmdfunc_47"

                stArray = Split(stArray(1), ",", -1, vbTextCompare)

                Ytpt = Val(stArray(0))

                Xtpt = Mid(stArray(1), 1, Len(stArray(1)) - 1)

                txtInput.Text = (Ytpt Mod Xtpt)

                GoTo 60

            Case "cmdfunc_57"

                'MsgBox("sttpt= " & StTpt)

                stArray = Split(stArray(1), ",", -1, vbTextCompare)

                Ytpt = Val(stArray(0))

                txtInput.Text = Math.Log(CDbl(Val(Ytpt))) / Math.Log(10)

                GoTo 60

            Case "cmdfunc_58"

                stArray = Split(stArray(1), ",", -1, vbTextCompare)

                Ytpt = Val(stArray(0))

                Xtpt = Mid(stArray(1), 1, Len(stArray(1)) - 1)

                txtInput.Text = Math.Log(CDbl(Val(Ytpt))) / Math.Log(Xtpt)

                GoTo 60

            Case "cmdfunc_52", "cmdfunc_53"

                stArray = Split(stArray(1), ",", -1, vbTextCompare)

                Ytpt = Val(stArray(0))

                Xtpt = Mid(stArray(1), 1, Len(stArray(1)) - 1)

                If glcmdfunc = "cmdfunc_52" Then txtInput.Text = mathDay.Lcm(Val(Ytpt), Val(Xtpt))

                If glcmdfunc = "cmdfunc_53" Then txtInput.Text = mathDay.Gcd(Val(Ytpt), Val(Xtpt))

                GoTo 60

            Case Else

                'MsgBox("sttpt= " & StTpt)

                If IsOper(Mid(txtShow.Text, Len(txtShow.Text), 1)) = True And CmdLeftBrk.Enabled = True Then txtShow.Text = txtShow.Text + txtInput.Text

                expression = EditedEqu(txtShow.Text)

                If IsValid(expression, False, False, False) = False Then MsgBox("Invalid expression") : Exit Sub

                Call Init0(expression)

                txtInput.Text = GetVal0(0.0, 0.0, 0.0)

                 End Select

60:     Cmdequal.Enabled = True

        CmdClsAll.Enabled = True

        txtInput.Enabled = True

        txtShow.Enabled = True

        AnsResult = Val(txtInput.Text)

    End Sub

下面為使用計算機計算之部份成果畫面

Figure 1  Sin(12)=?

Figure 2  SinD(45)=?

Figure 3  4+78+sin(45)=?

Figure 4  SinS(“45d23m56s”)=?

15.3 任意方程式輸入計算

本計算機相關函數計算因使用到VBcript語法，因此在txtshow文字方塊中以鍵盤輸入合乎VB語法之任意方程式如12+45+SinS(“46d55m12s”)+12^2然後按計算機中之等號按鈕”=”後即可在txtInput中顯示正確答案。

Figure 5  12+45+SinS(“46d55m12s”)+12^2=?

15.4 2D函數圖繪製

有關2D函數圖繪製程式設計，僅刊登極座標圖繪製部份供讀者參考。

  Private Sub CmdPolar_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CmdPolar.Click

        Dim stIn As String,  expXY As String

        Dim tBeg As Double, tEnd As Double

        Dim STresult() As String

        If txtEQInput.Text = "" Then

            MsgBox("尚未選取或輸入方程式及變數範圍,請重來")

            Exit Sub

        End If

        stIn = txtEQInput.Text

        STresult = Split(stIn, "=", -1, vbTextCompare)

        If UBound(STresult) <> 1 Then

            MsgBox("資料有問題???,請重來")

            Exit Sub

        End If

        expXY = STresult(1)

        MsgBox("expx_xy=" & expXY)

        tBeg = Val(txttBeg.Text)

        tEnd = Val(txttEnd.Text)

        MsgBox("tbeg=" & tBeg & ":" & tEnd)

        Call drawPolar(expXY, tBeg, tEnd)

        txtEQInput.Text = ""

End Sub

    Private Sub drawPolar(ByRef expression As String, ByVal pStart As Double, ByVal pEnd As Double) ', Optional ByRef coloruse As Color = Color.Black)

        Dim lastx As Double, lasty As Double, point1 As PointF, point2 As PointF, x As Double, y As Double

        Dim X1 As Double, X2 As Double, Y1 As Double, Y2 As Double

        Dim expression1 As String, i As Double, steps As Integer

        Dim ia As Double, ib As Double, la As Double, Lb As Double, l As Double

        Dim ErrorI As Boolean, lasterror As Boolean

        Dim Ltest As Single

        Dim xa, ya, xb, yb As Single

        Dim gp As Graphics = PicGraph.CreateGraphics

        On Error GoTo errh

        expression1 = EditedEqu(expression)

        Init0(expression1)

        steps = 800

        steps = steps * 10

        i = pStart

        lasterror = False

        Do While i <= pEnd

            ErrorI = False

            Mathday.mathErr = False

            l = GetVal0(0, 0, i)

            X1 = l * Cos(i)

            Y1 = l * Sin(i)

            X2 = XYFromUser(PicGraph, -10, 10, 10, -10, X1, Y1).X

            Y2 = XYFromUser(PicGraph, -10, 10, 10, -10, X1, Y1).Y

            If Mathday.mathErr = True Then ErrorI = True

            If ErrorI = False And lasterror = False Then

                If i <> pStart Then

                    point1.X = lastx

                    point1.Y = lasty

                    point2.X = X2

                    point2.Y = Y2

                    xa = point1.X

                    ya = point1.Y

                    xb = point2.X

                    yb = point2.Y

                    Ltest = Sqrt((xb - xa) ^ 2 + (yb - ya) ^ 2)

                    If Ltest <= glXmax * 0.1 Then

                        gp.DrawLine(Pens.Blue, xa, ya, xb, yb)

                    End If

                End If

            End If

            lastx = X2

            lasty = Y2

            lasterror = ErrorI

            i = i + (pEnd - pStart) / steps

        Loop

errh:

        ErrorI = True

        Resume Next

    End Sub

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