[DOC]: clarify that markevery[float] considers path length along drawn line #27842

Bug summary

markevery[float] is supposed to result in evenly distributed markers, but when y-data is noisy, its effect seems to "gradually" fade away.

Code for reproduction

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(1e3, 1e7, 1000)

fig, ax = plt.subplots(nrows=3, ncols=3, figsize=(9, 9), layout="constrained")

for i, ax_i in enumerate(ax.flatten()):
    ax_i.set_title(f"noise level = {i/5:.1f}")
    y = np.exp(x**0.1) + np.random.rand(len(x)) * i/2
    ax_i.plot(x, y, 'b.-', markevery=0.1, ms=10, markerfacecolor="r")
    ax_i.set_xscale("log")
    ax_i.set_yscale("log")

Actual outcome

Expected outcome

All subplots be like the one with 0 noise level.

Additional information

No response

Operating system

Ubuntu

Matplotlib Version

3.8.3

Matplotlib Backend

matplotlib_inline.backend_inline

Python version

3.10.13

Jupyter version

No response

Installation

pip