I have points \{(x_i,y_i)\}_{i=1}^n and values \{z_i\}_{i=1}^n and I wish to plot them as a surface plot. However, when using

```
surface(x,y,z)
```

I get the following error

```
*** IDENTICAL DATA POINTS.
NDP = 3772 IP1 = 454 IP2 = 455 XD=-0.66677 YD=-0.799619
ERROR DETECTED IN ROUTINE IDTANG.
```

Although I am pretty sure that there are no duplicate points.

To create a minimal working example, I extracted the points where the error happened:

```
A=[ -0.66677 -0.799619 0.0830287
-0.667204 -0.799619 0.0829778
-0.667952 -0.799619 0.0828899
-0.668957 -0.799619 0.0827716
-0.670145 -0.799619 0.0826315];
x=A[:,1];
y=A[:,2];
z=A[:,3]
surface(x,y,z)
```

This returns

```
*** IDENTICAL DATA POINTS.
NDP = 5 IP1 = 1 IP2 = 2 XD=-0.66677 YD=-0.799619
ERROR DETECTED IN ROUTINE IDTANG.
```

The first two points are close to each other, but they are not identical. Does anyone have any idea on how to resolve this issue or another way to obtain the surface plot?

**Side note:** Coming from a MATLAB background, I am trying to get a result similar to what

```
tri=delaunay(x,y);
trisurf(tri,x,y,z)
```

offers. I am not sure to replicate that or obtain something similar.