No points generated for z axis

ROOT
1

hi,
i’m trying to create a 3d random distribution of points using TGraph, but for some reason it doesn’t generate points for the z axis. here’s the script i’m using,

TCanvas *c1 = new TCanvas("c1","Efficiency",0,0,800,600)
Double_t x,y,z
Double_t j = 100
Double_t k = 4
Int_t n = 100
TGraph2D *dt = new TGraph2D()
TRandom *r = new TRandom()
TRandom *r1 = new TRandom()
TRandom *r2 = new TRandom()
	for (Int_t i=0; i<n; i++) {
	x = r1->Rndm(i)*k-k;
	y = r2->Rndm(i)*k-k;
	z = r->Rndm(i)*j-j;
	dt->SetPoint(i,x,y,z);
}
	gStyle->SetPalette(1)	
	dt->Draw("surf1")

i’ve tried different variations, but i’m trying to create the plot from random numbers, but all the examples have the graphs set to a predefined function. any advice?
image.ps (204 KB)

2

Your point are align on a line. See the attached plot.
Look how your generate x and y.

c1.gif796×572 9.09 KB