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Thread: logarithmic scale

  1. #1
    Join Date
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    Question logarithmic scale

    hi all,

    Could you, please, help me?
    When I draw the bar-plot with logarithmic scale
    scaleEngine = new QwtLog10ScaleEngine();

    and I have Baseline = 0; (it shoud be drawn starting from the 0, i.e. from the infinity for logarithmic scale, i.e. from the bottom of the plot)

    but values are drawn from the top, but not from the bottom of the plot...
    e.g. I have yMax = 10.0
    yMin = 1e-100

    e.g. values: 12; 0.1; 0; -0.1; -12;

    How can I do the following: The values equal 0 or less shouldn't be drawn at all, but values > 0 should be drawn from the bottom of the plot...

    I am using qwt-5.0.2 and qt3.3


    Thanks a lot!

  2. #2
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    Default Re: logarithmic scale

    log 0 or log (-n) - undetermined, and I don't see bars on the plot with this values.
    but if "baseline" setted to "0", why bars (with positive value) are drawn from the top...

  3. #3
    Join Date
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    Default Re: logarithmic scale

    Okay, I think I know...
    I'll just put baseline to minimum (yMin), and it's ok...

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