Re: [Gnuplot-info] Both positive and negative log y axis in same plot

[somesh <som...@gm...>]

Leo Butler wrote
> How about
> 
> f(x) = (x >= 0 ? x : 1/abs(x));
> 
> plot file using 1:(f($2)) ....
> 
> 
> Leo


BBands wrote
> That sort of approach is often useful in plotting certain types of
> technical analysis indicators. One way I have seen that done is to
> pick a pair arbitrary cutoff points near zero. You could try Googling
> for John McGinley. He wrote on the subject back in the 1980s. His
> solution was to plot a small slice of the chart just above and below
> zero with a linear scale. I add a hatch to the region to make the
> discontinuity clear. I haven't tried this in gnuplot, but Ethan
> Merritt demoed some tricks using the ternary operator that should make
> it doable.
> 
>     John Bollinger

Thanks Leo and John for the ideas!

I could do something similar to what I wanted by this:

f(x) = (x >= 0 ? log10(x) : log10(1/abs(x)));

then combine the following two plots (in linear scale) using multiplot ...
set yrange [0:4]
plot file using 1:(f($2)) 

set yrange [-4:0]
plot file using 1:(f($2)) 

The use of multiplot is to place two plots above and below the zero line.
Positioning is tricky but doable!

Thanks,
Somesh



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