Example 0: Compute Exp(x) and the approximation 1+x, as well as the error estimate x^2/2.
Problem 0: Compute Log(1+x) and the approximation x, as well as the error estimate x^2/2.
Object, Property and settings:
Object Property Setting Form Name frmExpApx Caption "Function Approximation" Label Name Label1 Alignment 1 'Right Justify Caption "x:" TabIndex 0 TextBox Name txtXvalue TabIndex 1 Text ".5" Label Name Label2 Alignment 1 'Right Justify Caption "Exp(x):" TabIndex 2 Label Name lblExponential BorderStyle 1 'Fixed Single TabIndex 3 Caption " 'Blank Line Name Line1 Label Name Label3 Alignment 1 'Right Justify Caption "Exp(x) - (1+x):" TabIndex 4 Label Name lblDifference BorderStyle 1 'Fixed Single TabIndex 5 Label Name Label4 Alignment 1 'Right Justify Caption "(x^2)/2:" TabIndex 6 Label Name lblPolynomial BorderStyle 1 'Fixed Single TabIndex 7 CommandButton Name cmdCompute Caption "&Compute" Default -1 'True TabIndex 8 CommandButton Name cdmQuit Caption "&Quit" TabIndex 9
Event Procedures:
' In (Declarations) section of (General)
' Project Name: Approximation of Exp(x) by 1+x
' Date: May, 1996
' Programmer: R. Berman
' Description: This program evaluates Exp(x) and 1+x
' and computes the difference. It also
' computes the error estimate (x^2)/2.
' In this example, we will not concern
' ourselves with datatypes, formatting
' output, or errors which may occur if
' the user gives inappropriate input.
' Version Microsoft Visual Basic 4.0
Private Sub cmdCompute_Click()
' Assign the value of Exp(x) and compute the
' difference Exp(x) - (1+x) as well as the
' error estimate x^2/2.
lblExponential.Caption = Exp(txtXvalue.Text)
lblDifference.Caption = _
lblExponential.Caption - (1 + txtXValue.Text)
lblPolynomial = txtXValue.Text ^ 2 / 2
End Sub
Private Sub cdmQuit_Click()
End ' End the Program
End Sub
Remark: You can add a graph of the functions to the form as follows. Add a PictureBox, then create the graph in any program capable of creating a Windows Metafile graphic. The following was achieved by creating the graph with Scientific Workplace 2.5 (using the Maple 5 Kernel), copying the graph, and pasting it into the PictureBox.
