[BUG] plot of sinc quite inaccurate

[simeonschaub]

Details

A minimal reproducer is plot(sinc, -40, 40), which results in the following plot:

This surprised me quite a bit, since I initially thought my function itself was numerically unstable. I would have expected plot to capture the smaller oscillations outside of [-20, 7] a lot more accurately than it did. I understand there is an inherent tradeoff between accuracy and the number of sample points, but perhaps the default can be tweaked slightly to show more relevant detail in cases like this.

Backends

This bug occurs on ( insert x below )

Backend	yes	no	untested
gr (default)	x
pyplot			x
plotlyjs			x
pgfplotsx			x
unicodeplots			x
inspectdr			x
gaston			x

Versions

Plots.jl version: 1.22.6
Backend version: GR 0.61.0
Output of versioninfo():

Julia Version 1.6.3
Commit ae8452a9e0 (2021-09-23 17:34 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: AMD Ryzen 7 PRO 4750U with Radeon Graphics
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, znver2)
Environment:
  JULIA_REVISE_WORKER_ONLY = 1

[mkborregaard]

This seems to be an issue with PlotUtils.adapted_grid