How to set Yaxis Minimum scale using using C#.net in Excel

I'm using Interop excel 12.0 to create a chart.

My assigned datarange to yaxis starts from 7/5/2010 till 8/29/2011. but Y axis on chart starts from 7/12/2010 and ends at 8/22/2011 however the chart line growth shows the datas from start to end

myChart.Chart.ChartWizard(xlWorkSheet.get_Range("A1", "B62"),misValue, misValue, misValue,misValue, Excel.XlRowCol.xlColumns, false,
                    "Spac开发者_C百科e Used Trend Report for databases DLP01P, DLP07P, DPN01P and DUV01P", "Date", "GB", misValue);
                Font f = new System.Drawing.Font(FontFamily.GenericSansSerif, 10.0f);

                myChart.Chart.ChartTitle.Characters.Font.Size = f.Size;
                chartPage.HasTitle = true;

                //Trend Line setting
                //Creating a series
                Excel.Series series = (Excel.Series)chartPage.SeriesCollection(1);

                //Setting the series to Secondary (y) axis so as to format the same
                series.AxisGroup = Excel.XlAxisGroup.xlSecondary;
                //Setting the trendline type
                Excel.Trendlines trendlines = (Excel.Trendlines)series.Trendlines(System.Type.Missing);
                Excel.Trendline trendline = trendlines.Add(Microsoft.Office.Interop.Excel.XlTrendlineType.xlLinear, 2,
                    0, misValue, misValue, misValue, false, false, misValue);

                //Creating a variable for yaxis and assigning the chart's y axis to the same
                Excel.Axis yaxis = (Excel.Axis)chartPage.Axes(Excel.XlAxisType.xlCategory, series.AxisGroup);

                yaxis.MajorUnit = 14;
                yaxis.MinorUnit = 7;
                yaxis.Format.Line.BackColor.RGB = Color.Red.ToArgb();
                yaxis.Format.Line.ForeColor.RGB = Color.Red.ToArgb();
                yaxis.MajorUnitScale = Excel.XlTimeUnit.xlDays;
                yaxis.MinorUnitScale = Excel.XlTimeUnit.xlDays;
                yaxis.MinimumScaleIsAuto = false;
                yaxis.MinimumScale = ?????

the minimum scale is taking only double values.

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If I understand you well, this is what you're looking for: in Excel a date is the day number since 1-1-1900. If you want to calculate that in C# code, keep in mind that in Excel 1900 is a leap year (which it is not, of course, but this originates from compatibility with Lotus 123!), so 7/12/2010 would be 40519.00.

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Try something like this, just change the values

{

        chartPrincipal.YAxis.ScaleRange.ValueHigh = 100;
        chartPrincipal.YAxis.ScaleRange.ValueLow = 0;

}