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I have noticed several time that the location of minor ticks in logarithm scale is not well define. See for instance the enclosed file HV_MinorTick_log.jpg

Here the x axis (frequency) is displayed in logarithm. I manually change both major and minor ticks. It seems that only major ticks are logarithm scale.

Have you already noticed this bug?

I've just checked the position of minor ticks. They are correctly placed.

The interval between minor ticks is not constant. For .jpg image, from 1 to 2 the intervals in pixels are:

(1.0) 0, 23, 45, 65, 83, 100, 116, 131, 145, 158, 171 (2.0)
(1.0) 22, 20, 18, 17, 16, 15, 14, 13, 13 (2.0)

x 1.0, 1.1, 1.2, ... 1.9, 2.0
Log 0, 0.0414, 0.0792, ..., 0.279, 0.301

Ratio log/pixel 0.0018, 0.00176, ..., 0.00177, 0.00176

Hence the X scale of your graph is a correct log scale even for minor ticks. If the step between 1 and 1.1 is close to the one from 1.9 to 2, this is normal, this is log scale. The step difference is certainly less than between 1 and 10.