Description

This subroutine specifies an explicit range for the x-axis of a user created 2D plot.

Syntax

SetUser2DPlotXLimits( plotid, xmin, xmax )

Parameters

plotid As Long

Identification number of the user 2D chart whose X-axis limits are being set.

xmin As Double

Minimum value along the X axis.  Should be less than xmax.

xmax As Double

Maximum value along the X axis.  Should be greater than xmin.

Example

The example below populates an array of data with a Gaussian distribution and creates a custom 2D plot with explicit axes limits in X and Y.

Sub Main

    'USER SETUP

    Dim xstart As Double, xend As Double

    Dim amp As Double, width As Double

    Dim nsamps As Long

    xstart   = -10

    xend     = 10

    nsamps   = 201

    amp      = 1

    width    = 2

    ' Create a linear array of numbers from min to max

    Dim xvals( ) As Double

    ReDim xvals( nsamps-1 )

    linspace( xstart, xend, nsamps, xvals() )

    ' Populate the Gaussian function to plot

    Dim xfunc() As Double

    ReDim xfunc( nsamps-1 )

    Dim curx As Long

    For curx = 0 To UBound( xvals, 1 )

        xfunc( curx )  = gauss( xvals( curx ), amp, width )

    Next curx

    ' Create a 2D plot instance

    Dim plotid As Long

    plotid = AddUser2DPlot()

    ' Dimension the plot object as Chart2D so we can see the object's methods and variables in the editor

    Dim plotobj As Chart2D

    Set plotobj = GetObjUser2DPlot( plotid )

    ' Set generic graph information so you can see where they show up in the plot

    SetUser2DPlotWindowTitle( plotid, "Window Title" )

    SetUser2DPlotGraphTitle( plotid, "Graph Title" )

    SetUser2DPlotXaxisTitle( plotid, "X Axis Title" )

    SetUser2DPlotYaxisTitle( plotid, "Y Axis Title" )

    SetUser2DPlotInfoText( plotid, "Info text entry" )

    ' Add the data series to the plot

    Dim plotseries( 2 ) As Long

    plotseries( 0 ) = AddUser2DPlotSeries( plotid, xvals(), xfunc() )

    SetUser2DPlotXLimitsAuto( plotid, False )

    SetUser2DPlotXLimits( plotid, xstart, xend )

    SetUser2DPlotYLimitsAuto( plotid, False )

    SetUser2DPlotYLimits( plotid, 0, amp*1.1 )

    SetUser2DPlotLegendLabel( plotid, 1, "A=" & CStr(amp) & ", W=" & CStr(width) )

End Sub

Sub linspace( ByVal d_start As Double, _

              ByVal d_end As Double, _

              ByVal num_samps As Long, _

              ByRef ret_vals() As Double )

    Dim cur_ind As Long

    cur_ind = 0

    Dim cur_samp As Double

    For cur_samp = d_start To d_end+0.0001 Step (d_end-d_start)/(num_samps-1)

        ret_vals( cur_ind ) = cur_samp

        cur_ind = cur_ind + 1

    Next cur_samp

End Sub

Function gauss( x_val, amp, width ) As Double

    gauss = amp * Exp( -2 * ( x_val / width )^2 )

End Function

See Also

Chart Scripting Commands