Re: [Gnuplot-info] log color bar: out of range data --> invisible

[BBands <bb...@gm...>]

As far as i know, negative values are a show stopper when using log
scaling. A fellow by the name of John McGinley devised a hack to plot data
that spanned 0 on opposing log scales by skipping near zero values and
using a mirrored (inverted) scale for negative values, but for normal folks
negative values are not defined for log scales.

     John

On Wed, Apr 1, 2015 at 12:11 AM, theozh <th...@gm...> wrote:

> Hi there,
>
> In a matrix plot with logarithmic colorbar scale it is clear that
> negative numbers cannot be displayed.
>
> set logscale cb
> set cbrange[1e-10:1e-4]
> set palette rgbformulae 7,5,15
> plot "Matrix.dat" matrix with image
>
> Therefore, I would like to display the negative values as "missing
> values", i.e. invisible (white or transparent).
> However, it seems that gnuplot gives these negative datapoints the color
> of the maximum value instead of the minimum value or treating it as
> missing data. How can I achieve that?
>
> Thanks for any hints. Theo.
>
>
>
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-- 
John Bollinger
www.BollingerBands.com