# Plotting pbrt-v3 Gaussian filter

I want to plot the Gaussian filter of pbrt-v4 with a radius $$(100,100)$$ and a standard deviation ($$\sigma$$) of $$0.5$$.

I would expect something like this:

When I plot the pbrt-v4 Gaussian filter with radius $$(100,100)$$ and $$\sigma=0.5$$ I get:

Is the 2nd plot correct? I varied the radius form $$1$$ to $$1000$$ but the the filter size changes only 2 pixels in total (I get a similar results). Any ideas? How does the correct plot look like?