Strange behavior y label in PGFplots

Question

I've noted a strange behavior of PGFplots y label with the following code:

\documentclass{report}
\usepackage{pgfplots}

\begin{document}
\begin{tikzpicture}
\begin{axis}[
compat = 1.3,
no markers,
grid   = major,
ylabel = $P_2$,
xlabel = h,
xmin   = 0,
xmax   = 60000,
% TRY HERE
% case 1      
ymin   = 0,
% case 2
%ymin   = 0.00000001,
]
\addplot[line width=1.5pt,red] table[x index=0,y index=1]{
  1.0000000e+003  2.7793697e-004
  5.5000000e+004  6.3359750e-007
};
\end{axis}
\end{tikzpicture}

\end{document}

Compile with case 1 not commented and with case 2 commented and after viceversa to see the difference.

Can somebody tell me why?

Is it a bug?

Answer 1

It is a bit hard to predict when the tick numbers are formatted with a common scaling factor (as on the x axis in both cases, and the y axis only in the second case), and when they are formatted in normal scientific notation (y axis in the first case), but you can control the behaviour with the axis option scaled y ticks=false (or true, depending on what you prefer).