help

help

Post by Subir Singh Lam » Thu, 24 Jul 2003 19:10:31



Hello,

I want to plot a graph with logscale axis both x and y ( as the values to
be plotted are in log). The difficulty is that the values for y-axis are
in negative logscale (base 10) i.e. -5.567890. Whenever I try to plot the
values with logscale axis (x and y) it gives me a messgae "all points
undefined". If I try to set the yrange as [-11:1.0] it gives the message
"y range must be greater than 0 for log scale!" . I am struck is there
anyway to get around it or I will have to forget plotting with gnuplot.

Subir

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help

Post by Subir Singh Lam » Thu, 24 Jul 2003 19:14:54


 Hello,

 I want to plot a graph with logscale axis both x and y ( as the values to
 be plotted are in log). The difficulty is that the values for y-axis are
 in negative logscale (base 10) i.e. -5.567890. Whenever I try to plot the
 values with logscale axis (x and y) it gives me a messgae "all points
 undefined". If I try to set the yrange as [-11:1.0] it gives the message
 "y range must be greater than 0 for log scale!" . I am struck is there
 anyway to get around it or I will have to forget plotting with gnuplot.

 Subir

 - -
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unsubscribe info-gnuplot

]]]]

 
 
 

help

Post by Hans-Bernhard Broeke » Thu, 24 Jul 2003 22:03:46



Quote:> I want to plot a graph with logscale axis both x and y ( as the values to
> be plotted are in log). The difficulty is that the values for y-axis are
> in negative logscale (base 10) i.e. -5.567890.

That's not what gnuplot expects your data to look like if have 'set
logscale' active.  It should be 10^(-5.567890) instead.  I see two
possibilities:

1) forget about 'set logscale' and just plot the logarithmic values as
   as they are.

2) undo the log-scaling before you present the data to gnuplot.  gnuplot
   can do that on its own:

        set log xy
        plot 'datafile' using (10.0**$1):(10.0**$2)

--

Even if all the snow were burnt, ashes would remain.