Double log scale

**guilhermecruz** · 02-07-2013, 08:26 PM

Hello,

I need to plot a graph with some mining data and it have to be in the format Double log/log, talking about the scale of the y-axis and the x-axis respectively. The log scale is quite obvious, but are there any way i could change the y scale for double log? (loglog)

This is a specific kind of graph called rosin rammler.

And this is the example of some data:

y-axis x-axis
Cummulative % Passing (O/S) Size (mm)
0.993 2000
0.9823 1400
0.9503 1000
0.8585 710
0.7302 500
0.6077 355
0.4182 250

Thank you!

**MrShorty** · 02-08-2013, 12:10 AM

If I understand what you are looking for, Excel does not have a built in double log option for a plot.

The most straightforward way I can think of is to compute the first log, then plot that on a log/log plot (comma delimited).

Please Login or Register  to view this content.

In the event you need more flexibility, calculate the double log of y and the log of x, and plot those.

Please Login or Register  to view this content.

In either case, if you need the axes labeled with the actual y and x [rather than log(log(y)) and log(x)], you can create a dummy series for each axis, then label it with Rob Bovey's free XY chart labeler add-in (a quick search of this forum should locate the download page for this).

**guilhermecruz** · 02-08-2013, 11:04 AM

Thank you for your reply!

But actually I don't want to calculate the log of my data. What I want to do is just my scale to be log and double log.

Look at the picture for understanding:

http://www.tungsten-powder.com/pic/p...scribution.jpg

My data keeps the same, but you can see that the scale of the y-axis grow in a different way than the scale in the x-axis.

**MrShorty** · 02-08-2013, 12:06 PM

But actually I don't want to calculate the log of my data. What I want to do is just my scale to be log and double log.

I can appreciate this. It really would be nice if the Microsoft programmers had anticipated all of our various specialty graphs and axis combinations and built them into Excel for us. Unfortunately, they did not. So this is not something that Excel will do automatically for us.

If you look at the various third party graphing packages, you may find one or more of those that can create this graph automatically. If you are extra lucky, you might even find an open source graphing package that will do it.

If you search the internet long and hard enough, you might find someone else who has put together a spreadsheet for this and made it publicly available.

If neither of those options is available to you and you still want to do this in Excel, I'm afraid you are going to have to bite the bullet and calculate the various logs. If you go this route a couple of observations:

1) I could not find a combination of logs that would give me the straight line graph like your example graph. On a hunch, I tested a semilog plot with log(y) on the y axis and the x axis as 1/X. This was the closest I could come to recreating the sample graph. You will first need an accurate idea of the transformation needed to get the plot you want.
2) If you decide to do this in Excel, this tutorial http://peltiertech.com/Excel/Charts/RecipAxisChart.html (and the related tutorials mentioned in the article) may be useful for describing the process of building these kind of graphs.

**guilhermecruz** · 02-11-2013, 05:02 PM

Thanks again and sorry about the late response. I will be looking for third party graphing packages and if I find one that matches I will post it here.