Setting Grid with with Log Scale

Hi all,

I have run across something that I can’t seem to get around. I am producing several histograms (TH1D), setting the y-axis to be on a logscale and also setting the grid on this axis. For histograms where the y-axis goes up to about 10,000 I get grid lines on the major axis ticks. So that would be grid lines at 1,10,100,1000,etc.

However, with histograms where the y-axis only goes up to 1,000 I get grid lines on the minor ticks as well. So that would be grid lines at 1,2,3,4,5,6,7,8,9,10,20,30,40,etc.

I’m producing a report with plots of both types and on first glance it is decieving seeing all the extra grid lines on one plot but not another. Does anyone know how to set the grid - i.e. choose on which ticks the grid lines are drawn?

Thanks in advance for any info!

John Carter

These grid lines are automatically drawn when the number of decades is less than 5.
In the CVS version, these lines are only drawn if the axis has secondaries and tertiary divisions.
For example, calling h->GetYaxis()->SetNdivisions(10);
will drawn the grid lines only for the primary divisions.