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| Public Class Form1
Dim x1(50) As String
Dim y(50) As String
Dim k As Integer
Dim n As Integer
Public Function vichislenie_function(ByVal formula As String, ByVal x As Double) As Double ' функция calculate для вычисления значения функции
formula = formula.Replace("x1", x.ToString) ' заменяем строковое представление х1 на числовое
formula = formula.Replace(",", ".")
Dim objScript As Object = CreateObject("MSScriptControl.ScriptControl") 'создает переменную objscript типа object, присваиваем экземпляр класса scriptcontrol
objScript.Language = "VBScript" ' устанавливаем язык VBscript
Return objScript.Eval(formula) ' вычисляем функцию
End Function
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim formula As String
Dim x()
Dim y1()
Dim y2()
Dim tol As Double
ReDim x(0 To 1000)
ReDim y1(0 To 1000)
ReDim y2(0 To 1000)
k = 0
Dim h As Double = 0.00001
formula = ComboBox1.Text
x(0) = Double.Parse(TextBox2.Text, Globalization.CultureInfo.CurrentCulture) ' преобразует строковое выражение числа в число с плавающей запятой
tol = Double.Parse(TextBox3.Text, Globalization.CultureInfo.InvariantCulture) ' преобразует строковое выражение числа в число с плавающей запятой
Dim nachalo As DateTime = Now
Dim konec As DateTime
Dim Reshenie As Integer = 1
Do
y1(k) = (vichislenie_function(formula, x(k)) - vichislenie_function(formula, x(k) - h)) / h
y2(k) = (vichislenie_function(formula, x(k) + h) - 2 * vichislenie_function(formula, x(k)) + vichislenie_function(formula, x(k) - h)) / h ^ 2
If (Math.Abs(y2(k)) > tol) Then
x(k + 1) = x(k) - y1(k) / y2(k)
Else
Reshenie = 0
Exit Do
End If
k = k + 1
ProgressBar1.Visible = True
ProgressBar1.Maximum = k + 10
ProgressBar1.Value = k
ReDim Preserve x(0 To k + 1)
ReDim Preserve y1(0 To k + 1)
ReDim Preserve y2(0 To k + 1)
Loop While (2 * Math.Abs(y1(k - 1) / y2(k - 1)) / (Math.Abs(x(k - 1)) + tol) >= tol)
konec = Now
If Reshenie = 1 Then
MsgBox("Решение найдено", vbOKOnly, "Успешно")
ProgressBar1.Visible = False
TextBox4.Text = x(k - 1).ToString() ' преобразует х в строковую переменную с 20 знаками
TextBox5.Text = vichislenie_function(formula, x(k - 1)).ToString()
TextBox6.Text = konec.Subtract(nachalo).Milliseconds
TextBox1.Text = k
Else : MsgBox("Решение не найдено", vbCritical, "Ошибка")
End If
Exit Sub
End Sub
End Class |
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