[Gnuplot-info] tics, mtics, and logscale

[Tait <gnu...@t4...>]

Consider the following:

reset
unset key
set xrange [2**4:2**8]
set logscale x 2
set grid xtics mxtics ytics
set ytics 1
set multiplot layout 5,2
  set title 'default'; set mxtics 8; plot log(x)/log(2)
  set title 'xtics, 8'; set xtics 4; set mxtics 8; plot log(x)/log(2)
  set title 'xtics, 2'; set xtics 4; set mxtics 2; plot log(x)/log(2)
  set title 'xtics, 3'; set xtics 4; set mxtics 3; plot log(x)/log(2)
  set title 'xtics, 4'; set xtics 4; set mxtics 4; plot log(x)/log(2)
  set title 'xtics, 5'; set xtics 4; set mxtics 5; plot log(x)/log(2)
  set title 'xtics, 6'; set xtics 4; set mxtics 6; plot log(x)/log(2)
  set title 'xtics, 7'; set xtics 4; set mxtics 7; plot log(x)/log(2)
  set title 'xtics, 8'; set xtics 4; set mxtics 8; plot log(x)/log(2)
  set title 'xtics, 9'; set xtics 4; set mxtics 9; plot log(x)/log(2)
unset multiplot

It produces output like: http://i.imgur.com/AvUUZ.png

In the default plot, you can see the minor tics are spaced logarithmically,
as one would expect. As soon as I set the xtics spacing explicitly,
the mxtics lose their spacing.

But the oddity does not end there. The "xtics, 2" graph is probably
expected. But then the behavior for powers-of-two mxtics is nothing like
the expected logarithmic spacing (that works normally when xtics are not
set explicitly). I can't explain the non-powers-of-two mxtics at all. It
appears the spacing is uniform (not logarithmic), but different after
the first xtic for some reason.

In any case, the help doesn't adequately explain what's happening here,
and I'm sort of wondering if maybe there isn't a bug or two. Can anyone
explain?