Hi,

I am trying to plot 3 sets of data using TNtuple with a logarithmic color/z-axis.

Actually in my case “SetLogz()” doesn’t work.

More precisely, it’s possible to make the z-axis logarithmic but it won’t be linked to the color code in the plot

Below one simple example :

```
#include <TStyle.h>
#include <TCanvas.h>
#include <TNtuple.h>
{
TNtuple* nt = new TNtuple("nt","","a:b:c");
TCanvas *Can = new TCanvas("Can","",200,10,600,400);
Double_t x[16] = {1.00, 2.00, 6.00, 7.00, 3.00, 10.00, 0.20, 5.55,
20.50, 9.75, 1.50, 8.00, 5.00, 0.95, 3.85, 8.70};
Double_t y[16] = {1.00, 2.00, 6.00, 7.00, 3.00, 10.00, 0.20, 5.55,
20.50, 9.75, 1.50, 8.00, 5.00, 0.95, 3.85, 8.70};
Double_t z[16] = {0.001, 2.50, 600.00, 0.00001, 30.00, 10.001, 0.00020, 500000.55,
20.50, 9.75, 280000.50, 8.00, 5.00, 0.95, 3.85, 8.70};
Double_t x3, y3, z3;
for(Int_t h1 =0;h1<16;++h1)
{
x3 = x[h1];
y3 = y[h1];
z3 = z[h1]; nt->Fill(x3,y3,z3);
}
gPad->SetLogz(1);
Can->SetTickx(1);
gStyle->SetOptStat(0);
gStyle->SetPalette(1,0);
nt->SetMarkerStyle(20);
nt->SetMarkerSize(1);
nt->Draw("b:a:c","c","colz");
}
```

Normally the point with z=280000.50 should be in red when z-axis is logarithmic, but it’s not the case.

Thanks