logarithmic graphing

[goman19]

BLUF: Are the logarithmic basis (not the base) and the min value independent variables when graphing logarithmically in Excel?

Details: I would like to graph vibration amplitudes, which are displayed logarithmically on both the x and y axes. I know how to change the axes to display logarithmically, but I can't seem to independently change the basis and the min value. For example, I want to display values on the x axis from 9 to 110. However, when I specify 9 as my min value Excel uses 9 as the logarithmic basis (i.e. 9-90 in base 10) even though I want 10 as the logarithmic basis (10-100) and just want to expand the visible portion of the graph a little.

To be clear, I want to use base 10, but I want the basis to be 10 as well. Before someone suggests it, I know you can edit the base, but that does not control the basis. Right now this is what Excel is doing:

• Base 10, min value/basis of 10: major increments of 10, 100, 1000, etc. (10*10^x)
• Base 10, min value/basis of 5: major increments of 5, 50, 500, etc. (5*10^x)
• Base 5, min value/basis of 10: major increments of 10, 50, 250, etc. (10*5^x)
• Base 5, min value/basis of 5: major increments of 5, 25, 125, etc. (5*5^x)

What I want is the following:

• Base 10, basis of 10, min value of 9: major increments of 10, 100, 1000, etc. (10*10^x) but the visible axis begins at 9.

Is there a way to independently manipulate the basis and the min value to do what I want?

 

[thisoldman]

If you want the horizontal axis to start at 9, you modify the vertical axis.

With Excel 2013:
Select the vertical axis for formatting. Under Axis Options, there is a section labeled "Horizontal axis crosses". Select Axis value. Enter 9.0 in the text box. Under Labels, change "Label position" from "Next to Axis" to "Low".

Yes, to change the vertical axis starting point to 9, you have to edit the formatting options of the horizontal axis.

I hope this helps.

 

[goman19]

I am using Excel 2010. Changing the axis value to 9.0 and the label to "low" shifts the vertical axis all the way to the left on the horizontal axis but does not change the visible range.

 

[thisoldman]

To accomplish what you want can be done; it does require a bit of work. I'm sorry I don't have a fleshed-out tutorial—I don't have the time to write one. I do have the time to give a brief synopsis of the steps and a link to my example workbook.

You plot the log10 values using non-log axis scales.
Two dummy series are used in place of Excel's built-in axes.
Error bars from the two dummy series are used to provide grid lines.
Original chart grid lines are removed.
Text from a separate cell range is used as dummy series data labels.
Axes scales are adjusted; built-in axis labels are deleted.
The plot area size is adjusted so the dummy series labels appear to be axis labels.
Error bars colors are changed to grid-line gray.
The dummy series are formatted to have no line and no marker, and it's done.

I do apologize for these cryptic instructions. I hope with the workbook as example you will be able to make sense of them.

Note that the Dropbox preview doesn't properly display the worksheet. The file should be downloaded to view and explore.
Dropbox - log-log_charts.xlsx