# Contour Plot of 1/(2*pi*sqrt(x^2 + y^2)), why is it square? How to fix it?

I plotted the contour plot of a function `1/(2*pi*sqrt(x^2 + y^2))`

.

The code is below:

```
contour_plot(1/2/(pi*sqrt(x^2 + y^2)), (x, -0.1, 0.1), (y, -0.1, 0.1),
plot_points=20, colorbar=True)
```

**The output result is not round, but square! Why?**

**How to fix it?**