Imports System.Math
Public Class Form1

    Function mvod(ByVal T As TextBox)
        Return (T.Text)
    End Function

    Overloads Sub mvivod(ByVal l As Double, ByVal T As TextBox)
        T.Text = CStr(l)
    End Sub

    Overloads Sub mvivod(ByVal n As Integer, ByVal T As TextBox)
        T.Text = CStr(n)
    End Sub

    Sub msub(ByRef l As Double, ByRef n As Integer, ByVal x As Double, ByVal a As Double)
        Dim del, ka, si, pa, d As Double

        del = (x - a) / x
        ka = a ^ (1 / 2) + x
        si = (Sin(x)) ^ 2
        pa = Pow(a, x)

        If (x <= 1) And (x >= 0) Then
            l = del
            If (l > ka) Then
                l = ka
            End If
            If (l > si) Then
                l = si
            End If
            n = 1
        Else
            If x < 0 Then
                l = x
                If (l < pa) Then
                    l = pa
                End If
                n = 2
            Else
                n = 3
                l = 0
            End If
        End If
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim x, a, l As Double
        Dim n As Integer
        x = mvod(TextBox1)
        a = mvod(TextBox2)
        msub(l, n, x, a)
        mvivod(l, TextBox3)
        mvivod(n, TextBox4)
    End Sub
End Class